I agree, but what if it's really their fault?!

I agree with you BusyMom. As a divorcee and veteran of post-marriage relationships, I'm here to tell you, blaming the other person gets you nowhere. It immediately puts the other person in a defensive position and that leads to more anger and more resentment (even if it is their fault).

My problem was that I would often make myself more responsible than was fair - to myself and my partner. I was once in a relationship where it didn't matter how much I apologized and pleaded about something that, in my partner's mind, I had done wrong, he just wouldn't let things go. No matter how much I tried to focus on solving the issue by our both taking on responsibility, he always got stuck on who's fault it was. It went so far that he held me responsible for his happiness and if he was in a bad mood or things weren't going well, it was somehow always my fault. Needless to say, I became exhausted and got out of the relationship. Also, I vowed never to put myself in that situation again and when I see early signs of someone whose problems are always someone else's fault, I head for the door - FAST.

I think I agree with most of what you said, but I'm not sure the delivery got me. What about the other person? What if they're to blame? If I over-scrutinize myself enough I'm sure I could make a case for why I'm to blame nearly every time, but if he cheated for example, is it really healthy or productive to deduce that I drove him into the arms of another woman?
Sometimes a healthy spoonful of vengeance is in order.