I've been working my charms on Wilhelmina and, judging by how she's blushing, it certainly seems to be paying off:
She's perhaps the only character you can romance in the game, the only one I know of for sure. You can befriend just about anybody and get them to really like you and they will act differently toward you, greet you differently, instead of a neutral generic greeting they may say something like "Hey, great seeing you again, I hope you're doing well." It's not a huge deal but I love that kind of reactivity in games. They'll even sometimes give you gifts and if they're shopkeepers they'll give you a discount. You can also go to the brothel and hook up with one of the ladies or gentlemen of the night there and get a really short sexy time cutscene. It will cost you 20K gold, though, so that better be some incredible sex for that kind of money. With Wilhelmina you can have a full-fledged romance, though. There's an entire quest chain for it. I don't know what the quest chain involves I only read up on it as far as knowing when to start the quest chain because there is a narrow window of "time" (in between a couple of specific main story missions) in the game when you can initiate the romance, so once I got that information I stopped reading to avoid spoilers. I haven't quite reached that point yet because I've been doing a lot of side content, but I'm close and in the meantime I worked my charms on her to get her affinity up to maximum. The blushing is this game's indicator of maximum affinity. At the end of the quest chain is presumably some hot steamy sex, eat your heart out @BruceVC