Her friends, in a nutshell. They hate you. You hate them. But you can't just be forthright about that, unless you want your romance to be really short and uneventful. So you have to force a smile and put on a happy face about her friends, rather than doing what you would rather do, which is choke the life out of that (expletive deleted) who's constantly telling the object of your affections what a loser you are because she just got dumped by some other loser and now hates anything with a Y-chromosome. It calls for a subtle and delicate touch, along with a quick decision about whether the target is actually worth the kind of AA fire you're going to get on your way into the drop zone.
My wife thinks that Budweiser commercial, the one that salutes the "wingman" who "takes one for the team" so that his buddy can get to know some other woman a little better, is hilarious, because she doesn't understand that, to men, that's not a joke. The "wingman" is just one of the many ways that men have evolved to deal with the nasty-girlfriend problem...