can anyone explain this

Ive been with assholes before and when they cheated it was no big shock they were already assholes but now ex he was literally the sweetest guy ever worshipped the ground i walked on, treated me like a Queen supported mentally, physically and sometimes financially. Accepted me and my attitude that most men hate. The list of things he did goes on but he likes to cheat online got caught twice , i just don't understand how men can treat you so sweet just to cheat. I expect it from the assholes but he really threw me off