One of the major problems that I recognized in my behavior is that I listened to my dBPDexGF, about her characteristics, and based on that - I idealized her. I didn't observe her behavior in an appropriate way.
I think it is actually one of the narcissistic traits in me, I automatically assume that I know 'something about something', and I disconnect myself in the respect of actually observing that.
So, things that she said and that I took for granted:
"I really believe that I can love in a special way. My feelings are extreme. I would do anything for a person that I love" - I believed this. It is actually true (but it lasts like 3 minutes

). And this is something that caused my hard detachment phase. I didn't want to lose this... .
"I feel so strong empathy. I literally cry when I see someone hurt". I misinterpreted empathy with sympathy. I thought that she is an angel. I wanted that someone feels that also for me when I am hurt.
Things about integrity, how loyal she is etc. Again, I listened, I didn't observe the reactions in a right way.
Things that she did for her friends, sometimes she did really beautiful things, but now I see that all of these things were done in the context that other see that she did them. For example, if there is a big audience that will see her action/gift/something, she will make it 'big'. In other cases, not so much, if anything. So, if she can get huge validation, she will do this. I believe we all have these traits in some extent, but this was an extreme case.
'Making sacrifice for others' - I also recognized this as very nice characteristic in her personality. For example, if some friend was in a trouble, 'she will do anything' to help her. But again, she would talk very nasty things about this friend earlier/before.
etc. etc.
So, now when I look at her behavior I see a lot of B$, things that are not consistent, things that I took for granted just by listening her words and accepting them as a fact.
When I realized this, it this it eases my detachment process... .
She is someone different, not the person that I imagined. In one way, this is a good thing. But also - it is a warning for me - I need to work on my inner self and recognize why did I do this idealization phase. Don't worry, I am in therapy and already working on this.

Did you experience something like that?