Hello! English is not my native language, so I'm sorry for mistakes. I had a relationship with a girl and I think she has BPD traits.
After these recent events, I'm completely devastated and haven't been able to recover for almost four months.
I will briefly describe the dynamics of the relationship below.
May 2024 - We have sex on our third date. She's quite reserved and withdrawn. I've never had such "strange" sex in my life. Sometimes it felt like she wasn't even present in her body. Now I know it's called dissociation.

August 2024 - Her period is three weeks late. She says I wasn't supportive enough at that point, didn't tell her I wouldn't run away or disappear, and she breaks up with me because of that. It was a bit weird because I didn't disappear during those three weeks, offering to pay for any doctor, any tests.

September 2024 - She gives me a birthday present.
October 2024 - I give her a birthday present in return, and she invites me to Turkey to the mountains with her

November 2024 - In Turkey, I proposed resuming our relationship. She agrees, but only on the condition that I pay for the trip. This was incredibly strange for me, but I agreed. We start dating again, but she's incredibly cold. The worst sex of my life, she's simply "off." We had sex four times in two weeks, and once, right in the middle, she simply said, "Let's end this now."
She only "thaws out" toward the end of the trip, toward the end of the second week. But upon our return, she's cold again. We meet, and I tell her I don't understand her behavior. I tell her I can't be in a relationship like that and suggest we remain friends.
She cried and in response, she says she's been told hundreds of times that she's "crazy," but she believes she's simply special and in good faith.

We've been friends for almost a year, and I help her a lot with her home renovations. We talked almost every day, met up, had lunch together. She told me, "What would I do without you?" It was a year of mental and emotional struggle for me. I loved her, but intellectually, I knew something was wrong with her.
In July 2025, she again invited me to go to the mountains together, but I declined because my mother was seriously ill.
At the end of August 2025, she told me that her friend (he's a mountain guide) had invited her to the mountains with his group. I asked if I could come too. She agreed. And then something terrible happened—she flirted with her friend and was incredibly cold to me, it was the most brutal triangulation. The three of us shared a tent, and she started sleeping with him at night in the same sleeping bag. She would even lean on me at night. I'm sure she knew what she was doing and did it deliberately. She was manipulating both me and him. She saw how jealous we were both; she felt like a queen.
When we were at the top of the mountain, she came up to me, hugged me, and kissed me (for the first time since our breakup a year ago).
After we descended the mountain, there was a party where she simply ignored both her friend and me. Her friend couldn't take it anymore and left party early. An hour later, she discovered this and ran towards the hotel.
The next morning, I couldn't handle the emotional intensity and left. She started texting me, asking how I was doing—the chase had begun. I responded, suggesting a meeting—but she immediately stopped texting, she realized that she still had control...
 and didn't wish me a happy birthday.
I suggested another meeting, where I proposed starting our relationship from scratch. She said we were just friends, but she kept asking me questions what had changed.
Two days after the meeting, I wrote a letter. She's silent. Five days later, I called her and suggested another meeting. She agreed, we talked for two hours, and she asked a lot of questions again, ultimately saying, "There are no feelings," and "Where have you been before?"
I wemt into low contact mode, and we haven't spoken since. It's been two months now.
Two days ago, I found out she's in a relationship with that friend from the sleeping bag.
I'm completely devastated. I have never feel such kind of emotions before. She just ruined me.
I'm in therapy and my doctor said she definitely has traits of BPD and bipolar disorder.

I want just vent and express my thoughts. I still love her but now it was mostly trauma bond. And I still cannot realize how she can be so cruel and harmful with me. I've done a lot of good things to her.

Is this a BPD thing, do we think?

Done the whole taking her to Tiffany’s, buying her jewellery which seems to get forgotten about.

When you get a bit older you kind of have everything, and gifts get a bit more difficult to buy, so often I would ask her what she wanted for birthdays and Xmas and it would be less about the expensive handbags and jewellery because she had it all. So the gifts would be things she really needed and wanted, but not really expensive items.
Now, me being a little bit on the autistic side, would then research the item(s) she wanted, and find out what the absolute best thing of what she wanted was that I could get her, or get her several different versions of what it was she wanted.
But because they were not expensive flashy things I would be told after a month or so that I had got her nothing for her birthday.

 I think it was her last birthday that we spent together she asked for a pair of shoes. She has a curvature of the arch in her feet, and she wanted a specific brand of shoe, so we went shopping and found a shop that sold them having looked in many shops, but there were none that she liked the style or look of. I said we can get some online, but she said she needs to try them on.
Needless to say, we couldn’t find any, but there is another expensive brand of shoe that she likes and we ended up there and I bought her some shoes. But because they were not the brand that she had been looking for, that turned into you didn’t buy me anything for my birthday. I’d remind her that I bought her the shoes and she would respond with they were not the ones I was looking for, and then would completely blank the fact I’d bought her them again shortly afterwards.

She would also take me shopping for my birthday, which would just turn into a shopping trip for her and she would come back with bags full that she had spent hundreds on for herself.

Flashbacks indeed!  Frightening how they can escalate everything. If a girl says to me 'I don't mind what we do' I take it to mean she's happy just being with me but say that to a BPD and it's a huge put-down.

I remember my ex sending back a sapphire ring I bought her - it was a wishbone-shaped ring which doesn't lie flat and she posted it back to me with a bit of flimsy kitchen roll over it and in a very thin envelope. It arrived absolutely flattened and with the stone out and I still have no idea if the damage was done by going through the post office sorting machinery or if she'd taken a hammer to it.

After an angry letter from me telling her where to go, she came into our local pub and said she hadn't purposely damaged it. I gave her the benefit of the doubt..but looking back, I should have stayed angry and NC and saved myself years of conflict.

This ring  - and many other items of jewelry I bought her - somehow slipped her mind years later when she accused me of 'never buying her anything'.

We don't generally do phone calls here.  While we don't want you to reveal identifying details, when you ask questions about specific issues here, the responses benefit both you as well as any others reading the posts who may be in similar situations.

Hello all, just joined, and it's been over two months since I left. I've been seeing a therapist, which has helped me. Still, towards the end of the relationship, I decided to look into the behaviors, and many of my Google searches led me to this website, which helped me understand what was going on. I believe he has undiagnosed BPD, and talking to my therapist, who also agreed, and also mentioned they had narcissistic traits and antisocial behaviors, besides all of the lies, using sex as more of a reward system or a weapon, pushing boundaries constantly, manipulation, gaslighting, and signs of cheating. He also showed odd behaviors, like when he was upset at me, he would pull hair off his body, and his facial expressions showed pain when he did it, because he knew this was a feature that attracted me to him, as if he was hurting himself to hurt me emotionally. And there were patterns. Whenever he was upset or mad, he would talk about poisoning me, jokes about murdering me, and burying my body, and how to do it so no one would find it.

Of course, I feel so stupid (I know I'm not supposed to) for dealing with this behavior and trying to help him. I ask myself now why I never left earlier, but no matter how hard I tried, nothing seemed to work. he would get worse. My therapist said I developed a trauma bond, which makes it incredibly difficult to leave even when it is an emotionally abusive relationship. I really am trying my best to move on, but I continue to ruminate on this entire relationship. I've been through breakups before and have never felt or dealt with anything like this. I thought it might be helpful to talk to other people who know exactly what it was like, because most people who haven't experienced it don't honestly know the emotional roller coaster it can be. So much went on, but these were the significant things that have disturbed me. Thank you for reading, and any replies that come with it.

indeed the smallest things ever.......Ex 'do you want to see the movie at 745 or 815?'.....Me 'either work for me, we'll be home a bit before that so it doesn't matter'....her 'that isn't an answer, can you not answer a question? You never listen to me'.....Me 'I heard you, I just have no preference, did you have anything to get done beforehand or no? I just don't care what time we pick both are fine.....Her 'of course you don't care, you never care about anything I care about. You're selfish. I just wish you'd be a man for once'....Me 'I do care, I just don't know what you have planned this evening. And what does this have to do with me being a man? and selfish? I won't even address that'....CUE MASSIVE FIGHT THAT GOES ON FOR 2 HRS, well....no movie and hours of silence and crying.

having flashbacks.

When you mis-comunicate, even if its about the smallest isue imaginable, you become their most hated thing: a liar, a promise breaker. Living w. a BPD loved one has made me speak more carefully. No one is perfect tho, and I still make mistakes, naturally. It depends upon thier level of dys-regluation on how bad I get it in return.   

Yes, this is something I left off my post. The way she treated you……. Well that’s the way it is going to go for the guy that is so cock sure that he is her new saviour. He isn’t. You are not. The only person that can save her is her.

My wife said of her current boyfriend, he really gets me and understands me. This was while she was still sleeping with me behind his back…… classic triangulation. Of course it was falling for it too, but he had been fed all the bullsh*t. After one time sleeping with her she said to me I can tell him if I want, he will believe her. Which told me she is more than willing to lie through her teeth. Needless to say I messaged him and told him, and received a response from him saying I had slept with someone behind her back, which was fabricated nonsense from her to feed the narrative that her ex was bad, and he is her saviour.

Remember when you said that she originally felt like you were the only nice guy she's ever dated?  Her current boyfriend was told the same thing...and so were the guys she dated before you.

BPDs have to be the victim in their own story, so they often tell how others have mistreated them and how terrible life is.  It's true in a way because they're mentally ill and life feels really tough quite often.  It's also unfair to you and others though because it paints a jaded picture.

As others have said, she unblocked you in the moment to see what you've been up to.  It was nothing more than that because so much is done impulsively.  Don't focus on that too hard.

No problem at all, that's what we are all here for.  Vent away when you need to!