I've got a little problem. Let me give a little background. I'm soon to be 27. My bf is a year younger than me. We dated the first time just shy of a year. At the end of that time (I would say about 2-3 months at the end) he became really cold and selfish. I finally confronted him about it which led to our break up. He stated he wasn't sure a relationship is what he wants in life bc he knows he's selfish and doesn't ever want to do anything he doesn't want to do. We broke up for about 6 weeks. I never once called him or texted. He called me like every 2 weeks at least just to say "hi". I would always keep the convos short telling him I don't want to be friends with him. Eventually he came crawling back saying how it was the biggest mistake of his life. BLAH BLAH BLAH. Things are then fantastic for the first 3 weeks and then one day it was like the light switch just flipped off. I can almost pin point the exact time it happened too. Funny thing is there wasn't anything bad that happened to set him off. We had just spent the day together, saw a movie and went to dinner. But at dinner his whole demeaner had changed. He's stopped being affectionate and sweet like he had been and the relationship is back to being all about him. My question is what causes people to switch like that? How do people lose that loving feeling in such a short period of time?