Clarine's totally interested in him when they first meet, too. I think some of Roy's crack pairing options are easily more plausible than about half of his official ones.

I proposed the political marriage thing to make sense of Roy's character given canon more than anything else-- I definitely agree that most of the paired endings were probably an attempt to give players a bit of that element of choice that they'd come to expect from Jugdral. Why they didn't jump right to FE7's system of paired endings for non-lord characters is a bit of a mystery, though FE6 went through development hell so that might be part of it.