I mean, if in a story two male (or two female) characters flirt and show a clear undertone of sexual or romantic attraction, the story is not listed as being Gen. It's called pre-slash, because while there is no overt kissing or sex, the inference is obvious that two same sex characters either wish to or will get together non-platonically at some point after the fic.
So how come stories in which two heterosexual characters flirt/exhibit desire but don't actually kiss 'on-screen' are still considered Gen?
Why aren't they pre-het?
Why is there that unconscious inference that the presence of heterosexual relationships don't violate General fiction's standard clause of "no sex or romance" but inferred homosexual relationships do?
ETA Underlying Question: What makes a story Gen?
This meta question is brought to you by a reader who's had to stop reading far too many so-called "gen" fics because of unexpected pushing of a disliked het 'ship. (Even if nothing physically happens, the constant presence of the unwanted 'ship hovering over every action and character development never fails to completely ruin an otherwise fine story. It's very disappointing, actually.)
Please, if you have any insight into this, please comment! I'm honestly curious to know why this situation exists, and why it's considered acceptable by... well, pretty much everyone. I don't think I've ever seen this question raised before, in any fandom. I'm not ashamed to admit this puzzles me.
ETA: Just in case, please note that my replies to your comments are NOT arguments -- just further questions. I'm simply, honestly, curious about this issue. I just want to know. Please, feel free to say anything you think or feel! The more input, the better the discussion! Thank you!