Falling out of love ?

My recent ex just broke up with me because he said he wasn’t in love with me anymore and wasn’t attracted to me anymore and didn’t want to have sex with me anymore. My question is how is it possible to just “fall out of love”. I’m the exact same person I’ve always been and he told me that I was the perfect girlfriend but he just can’t help how he feels. I can’t wrap it around my head how you can be the best to someone and it just stops being good enough. It’s been less than a month and he’s already on tinder.. seriously! For a year he promised me the world and a future together only to break his promises, my heart, and go on fucking tinder!? How is it humanly possible to just get over me so quickly because I know he used to really love me.