Many women have male friends as do some males have girl friends. If you are unable to attend the concert for some reason there is no reason she shouldn't be escorted by a male friend. It is obvious neither of you communicate well so start communicating so she knows how you feel and then listen to what she has to say and come to some rational decision regarding this problem. Just because women go out with a male doesn't mean there is a romance going on or that she is cheating. If the female friend is constantly going out with her male friend then there is a problem because she should be spending and he should come first. However, if her boyfriend is not willing to enjoy some of the things she does then there is nothing wrong with her taking a male friend.
