I've ran Descent several times, and had to change groups as many times. The change always comes when a specific thing happens: the heroes lose a quest. For some reason, even if I caution them at the start that the Overlord can and does win sometimes, they always get frustrated when they lose a quest and stop playing.
Now, I admit myself I'd prefer a role similar to a GM in a tabletop game. The winners aren't one side or another, it's everyone for having fun, that sort of thing. I toyed with the idea of just giving everyone, win or lose, all of the rewards listed for their respective victory conditions and then just playing less aggressive in general, with Heroes receiving all Relics they go for, but I wonder about the balance, then.
What say you guys? Something other than 'get a new group', hopefully.
(I'm aware of the Forgotten Souls co-op and have played it at my FLGS, but I'm hoping for something akin to this for for the campaign.)