My girlfriend is very secretive about her masturbation. I love to watch her and occasionally, she'll let me. Most of the time, however, she explains to me that likes to do it 'on her own' and keep our sexual encounters to purely sex.
Lately though, she has been a lot hornier and less 'discreet' when she masturbates. We will go to sleep at night and she will wait until she thinks I am asleep, usually 10 or 15 minutes. She will be on her back and will slowly slide her hand under the covers and lightly touch herself. After about five minutes of this, she'll carefully take the covers off her side of the bed and start masturbating more openly. I barely open my eyes and I can see her slide her finger up and down over her clit faster and faster. I can also hear the swishing noises as she rubs her clit (she gets very wet when she masturbates) and her paced breathing as she brings herself closer to orgasm.
Once she cums, she turns to the other side of the bed as her whole body twitches and convulses. It gets me so hot that sometimes, I cum without even touching myself. Other times, I wait until she seems like she's asleep and I take care of myself right next to her. Maybe she's really awake too and wanting to watch me. I'm really not sure.
Whatever the case, watching her masturbate while she thinks I am asleep is one of the hottest things I have ever seen. She's doing it more and more lately and I hope it keeps up!