Why do I put myself in the same situation over and over expecting the outcome to be different?

Last month I thought I was pregnant, boy was I glad when the pregnancy test was negative. I promised that I wouldn’t have unprotected sex ever again. It never occurred to me that I could still get pregnant while using birth control. That is exactly what happened, I believed this would never happen to me again, what are the odds. Just to be safe, I swore I would insist upon using a condom in additional to the birth control I was already on. Guess what, pregnant again by a guy I didn’t even like or know very well. Abortion #2.I never stopped to wonder why I was having sex to begin with. I’m not even in a committed relationship. My mom always had a boyfriend after she and my dad divorced. I thought it was normal. Come to think of it, I can’t remember the last time I wasn’t sleeping with someone.