I genuinely think it's because of me. We get along well otherwise but he has this tendency to hate everything that you like, if you like a game or a movie then he'll almost without exception say that he found the same game/movie absolutely terrible. Hence I reckon the minute he found out I'm a United support he decided that he hates us. He doesn't admit it and says he's always hated United but I don't truly believe that.
There were literally 2 cases last season where I found out we conceded because he was so fast to text me 'hahaha United' on WhatsApp that my 5-6 seconds delay on a stream did not catch up.