That's...Quite the title indeed.
"Just the idea of not using such an amazing hole, there's something seriously wrong with your boyfriend"?
I guess that explains why he's not the Hentai Protagonist this time around, cuz he doesn't like anal.
Well, _he_ didn't invite it over, so presumably that's why it's Uninvited in the title - though she obviously invited him to use it after having invited herself over.
reminds me of the story with the girl who asked the school pervert to train her asshole because her boyfriend didn´t want to. In the end the pervert convinces her to dump her boyfriend so she can get her ass pleased everyday by him