Oh, I have to add one more thing. Another way we hurt ourselves and stay sick WITH them is by buying into THEIR way of thinking, by believing that THEIR behavior has something to do with US. We are unable to separate the two.
What happens is, we either have compromised self-confidence and self-esteem to begin with (going into the relationship), or our self-confidence and self-esteem are eroded over time by allowing ourselves to continue to be exposed to the other person's hurtful behavior. Either way, we begin to believe that everything they do in the relationship is OUR FAULT because we allow ourselves to feel bad about ourSELVES (for example we think, "He cheated on me because I am too fat" or "If he loved me he would not do that"). And anyone and anything that says or does something that tells us we SHOULD feel bad about ourselves just digs the hole even deeper for us. Every time I have fallen into the habit of blaming myself for being treated badly like this, allowing myself to continue in a relationship that makes me feel bad about me, it has taken me YEARS to get out of it, to stop, and to rebuild my self-confidence and self-esteem. Now, though, after going through it so many times through so many relationships, I think I am strong enough to SEE it and get out of the relationship EARLY ENOUGH to prevent further damage to ME and my psyche. ANYONE who causes me to doubt or feel bad about ME is OUT--NOT ALLOWED in my life AT ALL. And that stands for ALL relationships, not just "romantic" ones.
It's like Iyanla VanZant says: When you see crazy comin', CROSS THE STREET.