The LitRPG harem novels I've read have featured little to no sex (and what sex did occur was mostly off camera). The theme was really more along the lines of the Hero male being incredibly awesome (OP to the max) and saving a bunch of different females from different situations. It really seems more like savior fantasies than sex fantasies.
Out of curiosity, does reverse harem exist in LitRPG? I’ve never seen it, but I’m still early in my devouring of the genre.
@Windfall and @Kidlike101 you two might enjoy reading The Hundredth Queen. I recently had some time to actually read for pleasure, and remembered that Amazon gave me a prerelease copy for free a couple months ago. So I read it, and it's a harem novel that focuses on the harem. The writing is good, but be prepared for every harem cliche ever. It's not exactly groundbreaking literature, but it's at least well-written and edited.