The avatar contest got me wondering... as soon as Worf sees K'Ehleyr in "The Emmisary" it's clear that he is really pissed off at her. Is there ever any explanation as to why? Any good speculation at least?
Klingons are weird. Noting in another episode (forget the title), Worf's (then unknown) brother visited the Enterprise. By Human standards, he was curt verging on downright rude to most of the crew. To Worf, by contrast, he was always downright friendly and showed great favouritism. Worf was deeply insulted by this - seeing the treatment of the rest of the crew as entirely correct and his 'special' treatment as major provocation. Also, from what little we saw / heard of Klingon romance / mating, there seems to be more in common with WWF cage matches than the Human concepts of same. So, the really pissed off reaction could be a "normal" Klingon thing, don't ask me why. Or, if Worf was reacting more humanly, perhaps the circumstances under which they had last parted left him with certain unresolved .... issues.
Perhaps just to emphasise a backstory. Obviously they did not part on good terms, and she did something that vexated Worf lol...
With a few exceptions during the first 4 or 5 seasons of TNG Worf was just generally pissed off at everyone, all the time.
She had a bit of a disdain for Klingon values & traditions, unlike Worf, who was raised without those in his life, & therefore took them very much to heart. It seemed as though their relationship failed because of that issue, & he still suffered from some resentment when she 1st arrived on the Enterprise