Why is my bf dumb when I fool around?

So I been datin my bf for like 4 months now and hes diffrent from my other bfs before and I was wonderin why hes mad why I like to have wif other guys too. I thought guys don't supposed to have feelings like that. He wants to break up wif me but I love him so much! My friend said boys arent supposed to cheat but girls can so he shouldnt be so dumb, right?