I think your husband has been trying to create new games with you and at the same time wants to explore sexuality more.

What you DON'T want to develop from this desire to explore and experience these exciting rushes that he clearly is looking to experience now, is you don't want innocence to turn into "Cruel Intentions". That is what the movie is all about, innocence turning into something that results in tragedy. You have shared that you have had a long happy relationship with your husband so far. It's ok to get creative, it can even be healthy, however it can also get dark and can end up destroying something that should instead experience "healthy" growth.

Also, there are other things that you can do together that create "rushes" that can be just as good. Some couples test their personal thresholds by going hiking together, or running marathons together. It's about the desire to explore which often does develop at this age both of you are at right now.