Angelblueeyes,
I hate to say this, but there's nothing you can do to stop someone from cheating -- it's their decision. The question is not whether you're doing everything you can to keep him from cheating; rather, the question is -- is he the kind of man who would stay committed to his wife regardless of whether or not he's getting everything he wants and needs?
I'd try talking with him again if it's bothering you so much, though men tend to tire quickly of repeated heavy discussions.
Innovative sex is great -- variety is the spice of life -- but even if you were everything he ever wanted in bed, it's not enough to stop someone who wants to cheat.