Personally, I'm fucking tired of the whole "will they, won't they" bullshit that seems to be in every romance story out there.
More often than not, it's done for the sake of dragging it out to an unreasonable level, just so they can milk the drama and audience engagement for all it's worth.
I can tolerate it if the romance is more of a background thing (Avatar), or if it's used primarily for the sake of comedy (Fairy Tail), but if you tell me that one of the main points of a show with romance in it is that "it's a slow burn," it's usually the point when I lose interest in it.
It's even worse if the media actually shows some actual progress with the relationship (i.e. they actually kiss), only for them to backtrack and undo it withing a few episodes or so. Star Vs. The Forces of Evil was full of that dogshit, and it's one of the main reasons why I despise the latter half of that show.