The problem with me is also one of my strong points. I pride myself on being able to adapt to difficult circumstances, whether it involves work, people, or anything else. Because of this ability, I have difficulty finding the border where I need a definitive cutoff point. I can never really tell when I'm being "screwed", because I can tolerate a lot more than the average person will put up with. Many circumstances in my life, I've had people try to point out that I was being screwed over by a person or situation, and I was always confused, wondering if those people were sincere in their observations, trying to manipulate me, or were just weaker than I am in what THEY would tolerate. I've always felt myself a better judge of what I should change, yet ironically, I never have any idea of when I should take action or what actions to take.
The most significant "walk-out" decision I can think of making was to finally end my first marriage, but unfortunately I couldn't make that decision without the presence or influence of another person. This person DID point out something that gave me a tool to identify a need for change, in that sometimes one must step back and try to see ANYTHING positive about a person or situation that drew you to them/it in the first place. If that's no longer there, it's probably a good idea to leave, instead of waiting around for things to get better. The hardest part about initiating change is that you HAVE to step out of your comfort zone to adapt.