I'm not 100% sure this would work, but one idea would be to exercise if you don't already. The rational is that exercise is suppose to increase testosterone over time (good for you) and obviously takes fat off (good for your partner if he joins you).

I don't think this will solve everything, yet it may be a step in the right direction.

Another semi-solution might involve reading the book, Ethical Slut, if you have any time on your hands to do so. It's about the ideology behind multiple partners. You're the best judge of whether or not that would be helpful to you.

To answer your question about the "high when first sexually attracted to someone," I think that's normal. I think normally that "high" is suppose to last for up to 3 years and then the relationship matures. Some couples, I think, "spice it up" now and then to bring some of that "high" back.

Good luck!