Quickly summarizing the situation so people may be able to understand it a little more. Our party was forced to brawl against a group of orcs in order to gain their respect to speak with their chieftain (long story, we had very good reason for doing this). It then became a battle royale. Our wizard was low health and next to our paladin, and had the idea to cast fog cloud to capture himself and the paladin within it so he could leave combat. He cast the spell, and then came down to the debate of if the paladin would get an AoO even though she was blinded.
Wizard was in threat range, but does an effect that causes an area to become heavily obscured cause the Paladin to lose threat range and the wizard be able to successfully flee to another area of the ring? Or does the paladin still have threat range and attack the wizard, even with fog cloud covering both of them? I looked over rules for 15 minutes after this situation but nothing comes up and it was ruled ig that it was fine to have AoO with disadvantage, but that just doesn't feel right. She might have heard wizard stepping away but the fog cloud was already in place. So by dnd rules does she get the opportunity attack or no?