So, you'd say, if that's not the focus at the beginning and the issue is brought up later and it stays and doesn't go away... It still wouldn't fit the tag cause it wasn't right away?
I mean staying as in, character is visibly asexual and their perspective is influenced by their lack of interest of certain subjects, another gets a boyfriend and so on... It still wouldn't because the story didn't introduce that side from the beginning 
I'm asking cause I'm genuinely curious XD (Hypothetical again) If it takes like 300 pages for the issue to be brought up (cause the focus was in something else in those 300 pages) then it's better not to tag it even if the characters are LGBT? :0
Wouldn't people be upset without the tag and almost everyone of the main cast not being heterosexuals?
Ahhh I don't mean to sound offensive, I mention this cause in another story of mine when I mentioned it people were upset and someone even messaged me saying they weren't ready to read a story with that theme even though they had a character like that xD So I was indeed wondering what was better.
(Yes, I'm well aware that person was immature and a jerk but I'm just mentioning it to give more context of what I'm writing)