My gf wont give up a friend, but there's a catch?

Okay, your girlfriend is BS-ing you. She isn't staying his friend because they've known each other for so long, she's staying his friend because she likes the attention from another man. She might be happy in your relationship but she likes to know that there is more than just one man in the world that finds her attractive. She's a compulsive flirt, it's not all his fault... he is honestly just picking up the signals. She knew how he felt and she held his hand anyway...that's not cool. Don't just hate this guy, you need to talk to your g.f too.