On the other hand, it would probably work if Dan were female. Or Kostyantyn were female. But then, the relationship itself may not be so one-sided. How would this affect the plot? It's an interesting thought, at least to me. [No, I'm not giving anybody a sex change, I'm just thinking out loud.]
Perhaps at some point I will do the Cliffs Notes remake of the story with a het pairing, just as an exercise to see how it would play out.
Another thing I need to revisit and possibly revise is Kostyantyn's reaction to learning Dan is gay. I keep forgetting they're in their early 20's and grew up in a slightly different generation than I did. Also, in a different culture. The only things that could explain him reacting strongly at all would be his individual upbringing, as his mom is very 'old country', or insecurity in his own sexuality. But that's something that'll work itself out later on.
Back to the actual writing part of all this.