"His woman," "her man," and any other version of this. Being in a romantic relationship does not mean ownership of another person and I refuse to acknowledge that it does, even if the people involved don't mind, or even like, being owned. I cringe every time I hear it.
Along the same lines of "life isn't fair": "Don't hate the player, hate the game," and "All's fair in love and war." Essentially, "I'm an ass hole, but its cool because I can justify my actions with pithy phrases."
"Common sense." If something is truly common sense, it would only need to be pointed out on rare occasions. Usually when people use this phrase they're blaming others for their poor communication skills.