There's a doujin I've been looking for that I had lost. Its name is only three words. It starts off with a guy and his girlfriend beginning to have sex. She asks to leave the lights off and the guy is having a little trouble getting into position. On the second page you can see the girl's face while having sex and if it doesn't make you go HHNNGGGG you are not human.
Anyways a couple of days later they meet up somewhere and by pure coincidence they end up at a love hotel. He asks if she wants to go in and she nods yes. She has a shower and comes out wearing nothing but a towel and he starts playing with her. On the last page he asks her if she's a masochist (in a playful way).
I think it's called "First time together", it's on exhentai but I can't find it.
Here's a hnggg-worthy doujin for your troubles:
http://exhentai.org/g/451156/3856de02d5/ 
