I love the drawing style. I'm kinda sad that the had sex but weren't together in the end -.-"
Well, it looks more like they weren't together yet at the end. Komachi makes it clear she has no romantic feelings at this point, mainly because she hasn't been given reasons to develop them. In other words, if Rie starts acting towards her not as a friend but someone she wants as a lover, then there's a good chance something might happen.
In any case, she didn't slam that door shut which is hopeful.