I don't know... I find this slightly refreshing. Most of the Yuri I read tend to be Sugar Festas which, don't get me wrong, I still love but you can only stretch the same concept for so long and keep it entertaining. Shit like this, where it shows that human relationships are not always all fluffy and cute and oh so great, are what really shows the strengths of a writer.
Yeah, they can fuck it up, and most times they do, but hell, I'm willing to shift through the garbo jut to find those hidden jewels. Another one that captures the "Dark" side of love.
Also, yes, there is such a thing as a sex-friend. You may not approve of the concept, and think it's impossible, but having had one of those in the past I can attest, sexual attraction and romantic feelings do not have any reason to be intermingled.