Not gonna lie... I kinda wanna see more of 1, 2, and threeeeeee. Like... there's so much to pull of romance stories. A person can do whatever and I'd be fine with it. Hell, I'll openly admit that I do 1, 2, 3.
Like with 1, there are situations where people do stagnant. Might as well talk about that.
2 is usually because of a joke? Or maybe there's a theme going on as to WHY the two haven't been together? Maybe the story is trying to say something? Or maybe the writer just wants to do something like this because they found an interesting angle.
3 is something I do a lot. I've been obsessed with games like Pato Box where you find little details that a character is into another character, although they don't openly show it. I wanted to do that in my stories where some characters don't appear to have chemistry, but that's something for the reader to re-read over and over again to notice tiny details.
I dunno what you mean by 4, 5, and 6.