This is excellent advice. (Just read the whole Captain Awkward).

Meanwhile, there is another way of dealing with your mother’s criticisms. Willfully refuse to understand what she is saying. Act like your partner really is the most handsome of the two, and you have no idea what she’s talking about. When she says your partner isn’t as handsome, say they look about the same to you, although your partner is a bit cuter because you always did like a guy with dimples. Squint at a picture of both of them and declare they’re “about the same height, give or take.” If she compliments another guy, just shrug and say, “He looks fine, if that’s what you like.” When she points out how your boyfriend looks different, just say, “Hmmm. Well they both look about the same amount of handsome, but I guess they look a bit different, now that you mention it. My boyfriend has more classic good looks, but the other guy looks perfectly fine too.”

It will drive her nuts.