Is porn a form of cheating?

jamie
Is there something wrong with me because i feel like my SO is a cheater because he watches porn?... he makes me feel stupid because he acts like theres nothing wrong with it. And when i bring it up he says i over react and that no other girl gets mad about their SO watching porn, and i was like hunny you're so wrong on that one. he gets jealous easily if a guy even COMMENTS on my pic even when i never reply back to them, yet he can jerk off to other naked females? i dont understand. he says he'd never cheat on me, but i dont think he knows getting aroused by another female is a form of cheating. The other night he took a shower that was way longer than he usually takes. And afterwards i asked if he wanted to have sex, and he came up with an excuse.