Somehow, I think some people are a bit too harsh with the author. I'm not pleased with the way it ended, as many other, but maybe the author just love this kind of story ? That's his/her right to do so and to draw such doujin. And reading it there, you didn't pay for it, so even if you're disappointed, there's no need to call the author an homophobe or such things.
As for the comedy tag, if you cut out the ending, the tag wouldn't feel that out of place, so yeah, the mood turns pretty dramatic in the end, but the rest was pretty much light-hearted and funny.