This is not unusual, but keep in mind that unlike someone you know irl, the reader is able to read the literal thoughts of these characters just as easily as the spoken word.
Bobby had more than one serious long term relationship, and in at least one of these we've seen him struggle internally with being a mutant, while dating someone whose family was hostile to mutants.
Edit: I'm misremembering. I think the issue I'm trying to recall was Bobby dating an Asian woman and HIS parents were racist. Its been a while.
Having him being closeted on top of that with no indication ever just doesn't quite work, because of the way the medium frequently exposes inner thoughts and angst. A newer character would be easier to pull off, but iceman has been around since the 60s. It stretches plausibility.
Peter Parker is just as old, and retconning his sexuality would be just as awkward here.