If you had a girlfriend who you loved more than anything and you were in a committed relationship with her, and your friend tried to take her from you from behind your back, what would you think of him? This [i]friend[/i] of yours threatens to take your love, your life, your future, everything from you. He would destroy everything that you value and cherish. She's your reason to smile, and he would dare try to take your everything from you. He would willingly pursue her, fully aware of how important she is to you. [b][u]Important Edit:[/u][/b][spoiler]After hours of cooperation between him, my girlfriend, and myself, everything was peacefully discussed. While our relationships with each other as friends may need some time to recover, the immediate issues between the three of us have been mostly resolved for now. There is no hate left behind, and for now, everything has been settled. Thank you to those who offered good advice. :)[/spoiler]
Throw some gloves on and fight. That's honestly how I would settle it. Best man wins. Olden days style. It's still a dick move though for a friend to do something like that.