I have two gay characters who are central to the story, but they aren't the main characters. It's revealed in the latter half of the story that one man has been persuing the hero, who is in love with the female protagonist. After he realizes that it was never meant to be, his relationship with his long-term partner is revealed. This happens late in the first book, but will be a bit more prevalent over the story arc (a planned trilogy). Is this something I should mention in a query letter? I know some agents and publishers still shy away from gay relationships and others embrace them, and I've used their relationship in a somewhat controversial way, so I'm really not sure what to do.