If nothing else, I wouldn't call it a tragedy, simply because it's not like future romance isn't totally out of the cards.
I mean, it's not what the ending seemed to be implying, but it really seems all it would take would be for one of them to slip up. And then it would suddenly turn into a will-they-or-won't they gay romance...
The implication on the other hand (that a moment's errant thought might have led to someone being forever prevented from being with the one they love in the furtue) is arguably genuinely tragic, though.
On the other other hand, purely narratively, this felt like if it went for another 20 pages, they'd probably have ended up together. So, eh.