Anytime a character is purposefully eavesdropping on their lover, but don't have the COMMON SENSE to finish the job and run off upset, I get irritated. Like, you went out of your way to listen in on them -- FINISH listening.
And then they wanna get mad at their lover instead of TALKING, and now their lover has NO IDEA why they're pissed. Come to find out, it was all a misunderstanding, and readers are supposed to gloss over the fact that this character 1) didn't respect their lover's privacy and 2) made a snap judgement against them.
Also, whenever I read a novel that has the hero/heroine be "this nice person who never gets love because they're SO different but SO misunderstood", I cringe. They're always brunette (because obviously blonde people are so arrogant and popular) and they always wear glasses (because you can't be attractive with glasses). They also make snap judgements towards other people, and the reader is supposed to agree because the other people are so paper-thin shallow and underdeveloped.