How do you treat your SO's friends?

My bf had a friend over yesterday just hanging out and talking. After he leaves, my bf makes comments about my "new bff". Apparently he is mad that I talked to his friend so much while he was here. His friend is just a really friendly guy that likes to talk. He is happily married, not like either of us were flirting. Just conversation. Should I have just sat there quietly or only talk to my bf? Usually I'm told I'm too quiet and need to talk more, but when I do I "get in trouble"? Just doesn't make sense to me.