I went out with a guy from college but just as friends. I knew that I would NEVER marry him & I knew that I would NEVER be exclusive with him either.

Maybe she never agreed to be exclusive with him....maybe that's just everyone else's assumption. There were times when I wasn't dating anyone else but we would just go out together to do something & we enjoyed riding horses together (I had several guys I rode horses with). If he had commented that I was his GF.....I would have been very angry also because I knew & made it known to him that we were just friends.

No one really knows what is going on with them at the truly personal relationship level....sometimes what it looks from the outside has nothing to do with the reality of the relationship.

If she hasn't been truly honest with him about her feelings & he's assuming that she is his GF.....then she needs to have a talk with him & set him straight rather than leading him on to think that way.....or maybe she needs a baseball bat to get it through his head that she isn't interested in him as a GF.........as I said....we don't know what is going on at the very personal level of their relationship.