I wait until my boyfriend is asleep to masturbate rather than initiate sex

This is something I, 22F, only do sometimes. The sex me and my bf have is great, very fulfilling don’t get me wrong. But I absolutely love to read smutty books with my hand down my pants after he falls asleep. I know he wouldn’t be hurt to find out I do this, I have caught him masturbating while I was sleeping one time when I woke up. We are pretty open about our needs and desires, but for some reason it feels even more delicious “doing it behind his back” Even though I wouldn’t care if he woke up.