Hmm...I think my self esteem was in tatters at the time I fell into this trap but in fairness in my case (and it sounds like most cases) he invested a vast amount of time in being the perfect, most adoring boyfriend in the world for some time before he "turned"
At that point, even a sane and together human being will initially be thinking ..."what happenned here, how can I fix it...what can I do?" and then of course he comes back to normal, you're all relieved and then he lather, rinses and repeats until you feel like you are going mad.
Mine displayed crazy making behavior.
At first, consistently showing his interest in me and that he was in it for the ling haul, displaying all the characteristics I admire most in a man, bowling me over with his sheer tenacity and how highly he thought of and regarded me, answering every question I asked in the perfect way. He absolutely targeted me and made me completely believe I was "it" for him.
then he'd start being odd. All of a sudden his daily calls and texts went to him disappearing completely for 48 hours and when I questioned it he made me feel silly and we had great makeup sex with me apologising.
The next time he disappeared for a week, and came back as if nothing has happenned and was more in love with me than ever. then it was 10 days. Then all of a sudde if I questioned him he'd be quite verbally abusive telling me to grow the fuck up.
My head was spinning. If I tried to dump him or ignore him, he'd be at my door crying begging me and telling me he knew he had issues but he loved me. The sex and chemistry was like nothing I had ever experienced and he'd put his head in my lap like a baby and beg me not to leave him.
It was absolutely fucking impossible to deal with and the reason I didn't walk away was partly because I had come to feel a desperate addiction to his adoration, and partly because I just wanted to understand what the fuck was going on.
I was literally OBSESSED. Couldn't work, eat, sleep, drink.
He finally admitted be was a "c**t. He said "that's just me, I'm a dick" and that it was basically all fun and games for him from start to finish. I don't think he had an authentic bone in his body.