My girlfriend and I have been dating for about a year. She is crazy about me and we have a great relationship. I perform in a band and today on the phone my friend asked me to text him my girlfriend's number. Normally, I don't feel insecure, but this seems strange to me. While me and my girlfriend are friends with him and his wife, I don't see why he needs her number. He is an attractive guy who is married, but still likes to flirt with girls. Should I be worried about giving him my girlfriend' number? Or is not giving it mate-guarding and lame?