I haven't played DA2, so if my assumptions are wrong based on the bit I know, please correct me (but don't be a dick about it)
But if there are 2 gay characters, and you get rivalry points for one for dismissing his advances, but the other doesn't, isn't that less a stereotype and more of a character design? Here you have a man infatuated with another, and when you turn him down he gets upset at you, he hates you. Think about that. Say you're straight and you flirt with a girl you have a crush on, you throw her a nice one liner you made just for her and she rejects you, how would you feel? Upset, right? And when you're upset, you tend to get a little more angry. Sure sometimes you instead fall for them harder, but if you cared about someone and they kept turning you down you'd be upset at them. Especially because them hitting on you and you turning them down would create an odd rift in the friendship.
I don't see this as a stereotype at all, in fact, I see it as a character portrayed as normal as anyone out there, someone who has a crush on someone and letting that person know, and being upset at the rift being created that grows farther and farther apart in size the more they try, them being the instigator of the rift and being human, not wanting to take acceptance of this. That's as normal human as you can get if you ask me