You hate his girlfriends
The second your male friend tells you about a date with a new girl, you analyze the date for bad signs. If he brings a girl around you, you don’t have the natural desire to get to know her. You find everything that any of his girlfriends do to be annoying. But if you really think about it, there was probably something likeable about all of them. You just happen to like him more than you like his prospects.