let's swash that buckle.

I agree entirely. And I'm someone who's usually all about pining/unrequited love--I think my biggest problem is that Gabaldon just doesn't bother to explain why John is in love with Jamie, instead assuming that anyone attracted to men would naturally be in love with him. It makes the whole thing ring hollow, which is such a shame when it's such a significant part of John's storyline and, as you say, John has so much else going on in his life that is complicated and compelling (and significantly more explicable).