it doesn't matter one bit to me what biological gender the characters are in a romantic pair. Relationships are damn complicated and with social issues everywhere no matter what kind of pair, period.
This is also mainly why I could never get into the yaoi or yuri genre: their portrayals don't show the many problems society gives the pair or the many facets of a relationship properly.
If I were to write a pair of two men or two women, I would give them the same fanatical dedication to believable realism I would give any original het pairing of mine.
Research, in these cases, is necessary. To understand a homosexual relationship for what it truly is, one has to understand the humanity of both people involved as well. Same goes for het pairings.
The only reason I can write het somewhat better: I am living that perspective myself, and therefore I am more familiar with it. However, it is still between two complex individuals, so it's not so much easier.