You should always be honest in your relationships...a relationship is nothing without trust!
It's funny because my boyfriend and I were discussing a similar topic last night. We are friends with this one couple and the guy freaks out every time somone hits on his girlfriend. My boyfriend is the complete opposite; he thinks it's really cool when guys hit on me, because he thinks, "Hey, all these guys are looking at my hot girlfriend. I must be a stud to get a girl like her." I think it's great that he is like that because I don't have to worry about hiding anything from him.