I might agree if that was all that we've seen Loras do, but it isn't. And I saw his recent scenes much differently. Instead of Loras not being able to hold a conversation with a girl, he just really didn't want to discuss the wedding and started rambling in a distracted manner about the pin/broach. Sansa is seeing their marriage as a dream come true and a chance for a much happier life, but for Loras it's a very different situation. And the scene of him jumping into bed made sense to me because he's: 1) mourning Renly and 2) not expecting to find another lover any time soon because of his sexuality. It's not as simple as him wanting sex because he's gay.
