It's the weebs, dude. I never understood why we need to use hentai tags for stuff that isn't hentai. Desert Stalker is the perfect example to show that these tags just don't fit at all.
I don't see how a cuckold tag wouldn't be much more descriptive than the dreaded ntr tag. Not saying that this game needs a cuckold tag, but sharing, swinging and the absence of cuckold describes this game perfectly. There wouldn't even be a discussion, if people didn't try to use their hentai mold for everything.
This game also features a harem, which doesn't fit the usual hentai highschool drama style.