I think this is an important topic to talk about. I can relate to the comments above.
I met my ex at a time when I was going through a lot of changes in my life. I was feeling vulnerable and lost and she tried to help me at first; but it was only for her own interest.
I'd feel obligated to do anything she wanted because I felt like I owed her something after all that she had done.
I generally tend to feel like I don't deserve the good things that happen to me. She knew this, and she would use it to manipulate me and make me do anything she wanted.
As @Abusedbysister said, I think this might be something common between manipulative and abusive people. They idealize you, give you all sorts of positive attention and try to help you every way they can; so that you feel like you need them or owe them something and can't say no to them.

I've also felt retraumatized in therapy. I was excessively attached to my first therapist, and the whole relationship with her felt like re-living the relationship dynamics I had with my father when I was a kid.
She was too focused on being "neutral" with me, to a point where she would just be cold and distant.
I used to see her as an authority figure and I'd desperately try to gain her approval.
She would never do any kind of introspection, and every time therapy wasn't working it would just be my fault.
At that time I'd just assume that just because she was the therapist she was right and I was wrong. I was so blind... I stayed in therapy with her for too long, and it did me more harm than good.