BPDFamily.com

I don't know how to handle this.
If I get too close, she is afraid of getting attached and then leaving her and hurting her more.
If I walk away she feels abandoned.
She told me with those words which surprised me a lot and removed all doubts that she was borderline.
It is a matter of being good for two weeks and another two bad.
What can be done to be close but not show him any love and make her live chasing you.
Or what can really be done?

mainly, go into your relationship with eyes wide open. know that there will always be difficulty, and that some of these things may come up again, and again.

know, likewise, that things can improve, despite that difficulty.

it will take some effort, a lot of which you likely arent accustomed to, but can learn here.

I do not know.
I'm tired of the situation.
We met 7 years ago on the internet,  met her current boyfriend and she disappeared without us meeting.
We dated 3 years ago and for a minor issue, she walked away.
At that time I did not relate to borderline, I just blamed myself a lot for that.
She went back to her ex-boyfriend after that, well it really seems like a on and off relationship.
Now I greeted her at the beginning of the year for her birthday and she told me that she had abandoned her and there I began to relate and said but as if she is the one who left and returned with her ex.
And that he had missed me and this and that.
 We started talking but due to the quarantine we couldn't see each other, so we started talking for hours on the phone.
It turns out that she confesses to me that she was still with her boyfriend, although now I think he came back in the middle of his quarantine, among other things, due to financial problems.
The quarantine ends and we start seeing each other behind her boyfriend's back and then she leaves him.
There I thought that at last things were going to work out but he falls into depression and first he does not want to see anyone and then he tells me that he began to miss him, I could not believe after having painted it as a terrible Narcissist although I think that is how they usually talk about their "past" relationships.
And here we are with her indecisive between one and the other.
But I'm tired of this triangulation and hysteria.
What I can do?

From everything I've learned the best advice I can give you is focus on yourself, show up as the best version of you, be outcome indipendent and don't have any expectations. If you can do that you'll have half a chance.

You can't expect non pwBPD out of a person with BPD, so set your boundaries, stick to them, do the above and roll the dice on it.

It can be very emotionally and mentally tiring.
Do you have an ideal outcome in mind?

I'll walk on eggshells here myself, to avoid giving you any blatant stay/leave advice since the site officially disapproves; so read between the lines as you will ;)

Be very careful to not box yourself into an inescapable position, do not think that crossing some imaginary Rubicon and great show of commitment will improve her mental health. Indeed you may well come to regret having left yourself without a good exit strategy if you find yourself trapped in a toxic or outright abusive relationship. Take even more cautions than you would with a normal romantic partner; as I saw someone on the forum recently advise, double or triple up your efforts to avoid accidental pregnancy for example - because that may make both your lives a living hell (even if the child were aborted, it may cause more long-lasting mental health symptoms for her specifically in relation to you). Also, your friends might understand that you're bedding a crazy person, but your relatives are not going to be able to see past her shiny happy facade - they'll think that she's wonderful and you must just be to blame for any of her problems. It may well strain or ruin your relationships with siblings, parents or others who do not know what BPD really is - or think reading a Wikipedia article makes them an expert qualified to dismiss her "eccentricities". Probably look into "male victims of domestic abuse" resources in your area now, just to bookmark and be aware of just in case you need them in the future.

Best of luck bro, however you proceed.