BONUS. Everyone Loves Me - not sure if they are online friends (hence bonus) but while they admire each other's gaming, etc prowess online, they unknowingly dislike each other in real life.
(Can't think one that hate/dislike each others irl, but at the first encounter where the name was being printed wrongly in a set of name cards, they each think the other one were uncommon)
2. The Flowers of War (2011) - found this one scowering through MDL because it has the Nun FL tag, but not sure if this is correct to what you're seeking