I recently received a review for my book Riding Partner where I received what I perceive as one of the best compliments I could receive from a male reader. I got the men "right." (You can read the full review here if you'd like.) Because to be honest, one of my worst fears in writing M/M romance is that the men come across as women with penises.
Guys don't think like women do. And maybe I have my growing up years where I was the only girl with two other guys in the Talented and Gifted group. Or maybe it's because I'm a sf geek at heart, and so I play with our local science fiction society. I even join in on the boffo sword fighting, because it's fun to try and beat each other up with pvc pipe wrapped with foam insulation and covered with duct tape. DIY shows are my heaven, and I could wander around a hardware store/lumber yard as easily as a book store. I'm a tomboy and proud of it. But even so, the way I think isn't the way guys think.
So my partner gets to bear my questions. "Honey, if you were in this situation, blah blah blah, how would you react?" "Honey, what do you think about this?" And so on. Luckily he's a writer too so understands the writer's curiosity and the writer's mind.
Even in heterosexual romance I want to make sure the men are, well, men. But when it comes to writing homosexual romance, with two guys, I want to make sure they're both guys, you know? Because two men finding love is infinitely sexy.