He's gay!
*He gets married to a women*
Don't worry, he's bi!
These kind of stans are always looking for the cheapest proof possible, such as if they look at someone of the same sex for too long or hug someone in their group who they've lived with, practiced with, grown up with, and so on.
What's the wrong with an idol being straight, and why do you worry so much about their sexualities? It's not like they'll marry you if they turn out to be a lesbian or whatever.
It's THEIR sexuality, not yours to put labels on