I was not actually sure if the intention was merely playing with the whole running gag of V being so ambiguous, but my personal take on it is that they are indeed a same gender marriage. Of course, I am projecting here, and I respect you wanting V's gender to be a mistery. Clearly in this case if I am able to get to that conclussion, is because you wanted to leave that possibility open, for what I am thankful.
My point here was, even if you are a straight male, you do not need to worry about your ability to portray an acceptable gay character or relationship, because for me, you already did. That is, of course, my view, and I am not implying that V or Inkyrius are one gender or the other.