Didn't they touch on it enough though? Jun clearly loved Miura, and was even asking for her to stay with him even when they'd be long-distant. But it was said countless times that despite his love he could never get hard.
If his love was still questioned, at the end of Chapter 13 in the translator's end card, it said "The best way to get over a heart-break..." He was clearly heartbroken they broke up.
That's what I'm trying to explain. The story shows signs of Jun being a Homosexual Biromantic and I can recognize that but the story doesn't know those words and the meaning behind them and thus makes the story a lot more complicated than it could be if they did.
Are you saying it'd be better if they outright labeled it? personally I think it explored it the best it could in manga form since it was pretty obvious that Jun loved her despite his homosexuality. maybe in the novel it was better explained though.
I feel like this was a very realistic outake on gay people and their feelings but the one crucial detail it missed was the difference between romatic and sexual attraction. While I think that it got touched apon a bit, it wasn't really explored. A man can love women but only get hard from men. It exists.