You are so right, if he dated KW she would get the same treatment. The girlfriend of Nic Rasenti who is now filming in SA with Sam and who organized the birthday dinner for Sam tweeted something very true: "have you ever read the comments on pictures of famous men's partners/spouses on SM? wow. Just horrifying. Women are so fucking mean". (@nicolereichlin). She tweeted that after Mackenzie got so much hate on one of her pics.
If anyone is interested, I found this video of Ashley Judd speaking out against online misogyny a couple of months ago. Obviously, the abuse that she has received is greater (if you thought women were bad, men are even worse *shudders*) and not everything she talks about has happened here, but this is still so very relevant regarding MM (and others ofc):