George remembers Marietta as the best friend of that one girl Harry dated before his sister, who then betrayed the DA and got them all in trouble. As it is, George has gotten over the whole holding a grudge thing, though it's safe to say he wouldn't trust her very much, so he'd just be the more distant side of normal - but he's busy with the shop and being a newlywed anyway, so. :P If she's friends with Roger though, they might see more of each other, because Roger is George's heterosexual life partner.
CHO, on the other hand, is much closer with Marietta, even if she thinks it's time to get over the past. ;) It seems like Cho and Mari counteract each other, because Cho is sweet and friendly to most people, even and including Hermione though we don't have one and is very much past Hogwarts drama, having very much come into her own as she's grown and matured. Definitely some plot here, whooo~ :D