You know, stuff like love interests, sexuality, and the like have pretty much permeated any aspect of modern media in culture, just look at any pop song in the last 30 years. The only place it didn't find it's way into is with Western Cartoons, and while there may be implications for humorous purposes, like showing Fluttersy's underside in the Super Speedy Cider Squeezy, for the most part it's just not a thing, and honestly, I'd prefer it to not be a thing.