As a D&D hater, I don’t think this is a problem of the game, or even of the forums. Your partner doesn’t seem like the kind of person that can handle someone disliking something they like, and considering everything that has been happening in the past few years - or really, ever - with Wizards of the Coast and D&D, there’s no place where you won’t find people - rightfully - criticizing it.
If he truly loves it, just find people with similar taste and play with it them, taking opinions from random online folks so seriously to the point of considering dropping his hobby is a terribly harmful outlook, and not just centered on tabletop gaming.