I think it isn't necessarily sex that I miss, it's the intimacy that comes with it - like you said, the flirty play and stuff. How can you work on intimacy without necessarily having sex?
You can't very well tell your man to flirt with you more.
Also, I love kissing and my boyfriend doesn't really seem to like to kiss much - I feel that's a really key part of intimacy for me and I'm not sure if it's something he's self conscience about, if it's me, or if he just doesn't get into kissing much.