It could technically be made into a het one but...it feels less guilty if it's BL...if that makes sense.
'-'
Like, the motives for why make more sense if it's BL.
The betrayal, if it's gay, is usually perceived strangely as less painful. "At least he didn't cheat on me with another woman."
In reality, I think that experiencing it is still horrible.
Have you started other stories?