Forced drama. I hate it when the author makes the protagonist become stupid or have trust issues out of nowhere. The worst forced drama I've read and made me stop reading a really good story was chapter 49 of 50 Tea recipes from the duchess. There the author made the protagonist act out of character and become stupid, and that was the second time it happened.
Forced romance/superficiality. I get that she/he's hot or is the kindest girl/guy you've met, but you're just needy or horny not in love! This one makes me mad. They haven't spoke yet, but fall in love as if he's the best man/woman in the world. Most manhwas, mangas, novels, and so on do this.
Forced couple/Drop the romance. Face it author! Your couple doesn't work. She/he could be happiest and grow as a person more with that other guy/girl.
Or, that romance sucks! He's a creep for fucks sake. She's a great woman and doesn't need that romance, she doesn't want it and is in the way of the story. And if she finds anyone else, it has to be a better person than that creep! Like in the story I raised Cinderella preciously.
Not asking again. I understand it author, you want misunderstandings. But anyone who cares would ask again what the other said. If they don't care enough to ask, why would I care about them and believe they could become a couple? If the protagonist has a problem with her hearing and never asks the romantic interest about the things said, what makes me think such a thing would change when they're a couple. It's a doomed romance for me.
Tell them to get the fuck out. I also hate it when they're interrupted and leave their conversation for later, and depending on how bad the author forces it, they may forget and talk about it months or years later. You want to say something? Say it in front of those people who interrupted or tell them to GTFO.