Boyfriends

Why is it that they think that if you talk to another boy you are going to dump them but they can talk, flirt or be all over another girl and they are just friends. I dont understand why I cant get mad at that but he can get mad at me for talking to one of my best friends just because he is a boy who has a girlfriend. I dont see why he should flip about me having a pic of me and him on my phone along with pics of me and my boyfriends and my friend and his girlfriend along with pointless other pictures of things. but he can tell another girl that shes how and she looks like she would be good in bed. I guess that i just dont think like a boy but I still dont think that its fair.