I read this and it stuck with me.

"But yes, when it's the hot cheerleader hitting on Mr. Blueballs, the 20-something guy who couldn't get the popular girl when HE was young"

Some guys get to bang a cheerleader right from the outset. Other guys get there by a circuitous route. Who are we to judge? And who are we to take their happiness away? If he wants it, and she wants it, why is it anybody else's business? It's not going to hurt them. Until a third party shows up. Let them make their own choices in life.