I am straight, and Im not really offended by the inclusion of a possible gay romance in the game, you get to make the choice right. Its a smart move to leave the choice to the player, since they cover a wide range of demographics. Besides if you are getting pissed at a fictional character hitting on your fictional character you probably have bigger problems to deal with.
I have made peace with the fact that times are changing, and these things are becoming more mainstream, and the fact is its a lot easier to take it all with a grain of salt, then flip out about it, and have it ruin my gaming experience.
When I play an rpg, I like to put myself into the game, create a character similar to me irl, and its hard for me to relate to a lot these kind stories lines. So its bit strange, but not offensive. I think most "straight male" gamers would probably just ignore or avoid those parts of the story, since they don't really make sense to us.
If a homosexual storyline was forced upon my custom made protagonist then, yeah it would be a bit of a problem, because then I would not really be able to relate to story at all, and I couldn't really "role play" it either since I have no knowledge or experience with the subject. It would just be weird to me.
This is why I always play male melee oriented characters. I feel like I really get into the games better that way.