If I must defend it, I'd say that after all his incredible adventures I guess Kirk has faced down every type of fear there is.
Actually, Kirk never feared rejection because, as he quipped to Spock in "Conscience of the King"—"I'm the captain." (He picked up Lenore just 140 seconds after she entered the party. He's even faster when he cranks the space wolf up to 11.)
Then Gillian dissed him at the end of ST4. The look of surprise on his face was priceless. Hey, even Fonzie lost his cool once.