All the time,
@Swift
"I should have left the first time he hit me"
"I should have left when he told me about how he got with me for personal gain"
"I should have left when he broke the first bone I ever broke in my life"
"or the 2nd"
"or the..."
So on and so forth. I could go on and on, there are so many things that make me go "ugh! why the f*ck didn't I leave after that!?!!"
But I'm looking at it in hindsight - and all at once. The abuse didn't start out with me getting bones broken, having guns held to my head, etc. It started out as just manipulation, without any serious emotional, physical, or sexual abuse. He took his time. He built it up, he ramped up into the hardcore abuse. He made sure that I was sucked in hard enough to not leave, before he started doing the shit that would make others leave.
The thing is, by the time the abuse got to the "heavy" point, I wanted out so badly, I wanted out of the situation, but I couldn't bring myself to do it, because I was so afraid, and manipulated. I -wanted- out, but I could not do it, until his torture kept me awake until the point where I was driven literally f*cking insane. I had to be psychotic to free myself from that. For me, that really illustrates how strong of a grip he had on me - now -not- in control I was, in regards to freeing myself.
I also had never had any experience being abused by a partner. I never had experience living with a f*cking psycho. I never had been exposed to the sorts of things he did to manipulate me, I never had to deal with being hit by a partner, I never had to deal with any of that shit he did before. So, because I had never seen that kind of abuse first-hand, I fell into it more easily.
I am sure the same things apply to a whole lot of us.