How do some men love someone and marry somebody else ? What is the thought process like?

My ex (33M) and I (28F) told each other that we still loved each other in June 2024, the same month he married someone else. He told me he had to marry somebody his parents approved of , had to be from same community, background etc. I get that he is a bad person for what he put me through, but how does he live with himself ? How does he sleep next to a woman knowing he still loves someone else. The wife also knows about his love for me but that he had to settle for her. The reason for my post is I’m confused, how can somebody live like this? I still can’t think of somebody else romantically. How do they do the charade of happy house ? The wife has seen all texts and call logs and everything, she still married him?!