I swearrrr Killian and Edith are my favorite OI couple
It might have been a typo and they might have ment OP, but I looked it up and this is what I found:
"OI couples" refers to romantic pairings found in "Otome Isekai" genre stories, where the female protagonist is usually transported into a fantasy world and ends up with one of the male characters, often a prince or a powerful figure; essentially, it means a couple from a female-focused fantasy romance story.
Hope that helps!ヾ(❀╹◡╹)ノ~
Jaehyuk unapologetically being obsessed with Garam got me giggling and kicking my feet