1-he is both their ex's 2-kyosuke did something that why he didn't contact her suddenly 3-he was in reality interested in kyosuke and was going out with her because he couldn't have kyosuke...kind of vendetta
that'll be different and a unique addition to the story but I doubt it, bisexual representation is so rare in stories, even rarer when its a straight story :/
1-he is both their ex's
2-kyosuke did something that why he didn't contact her suddenly
3-he was in reality interested in kyosuke and was going out with her because he couldn't have kyosuke...kind of vendetta