Why do people say they fall in and out of love?

It's normal, it happens to most people. Basically what it means is you still love that individual but the spark and spontaneity that was in the relationship before seemed to kinda disappear. It often happens when people stop doing what they did in the beginning to fall in love in the first place. It can also be from not trying new things repetition in a relationship could also cause that lack of interest. It just takes that one specific action or moment to bring the spark back that makes you remember like wow, this is exactly why I fell in love with her/him in the first place.

he's an a$$hole.fullstop.

because they were not in love to begin with ---- you dont fall in and out of love ----- when you love someone its forever ----- even if you are not together even if you will never be together ---- if you fall in and out its infatuation its lust its not love

mean.

Personally its happened to me, and its not something you can control no matter how much of a good person that person is with. It could just be he had mixed feelings about you. Some days he was in love with you, and he knew why. Some days he knew why he wasn't in love with you, maybe the flaws stuck out. Flaws can be your personality too.