No matter what a guy has or who he is with, he is not satisfied.
Grant's Law is derived from the actor Hugh Grant. Hugh Grant was lving with Elizabeth Hurley one on the most beautiful woman in the world and wasn't satisfied. So he picked up a crack 'ho on Sunsent Blvd.
Dude 1: I can't believe Nelson. He is with that hottie Cicely for six months and she caught him with making time with that hood rat Heather last night at the club.
Dude 2: It's Grant's Law. Guys are never satisfied with what they have.