Short answer is you don't have to have one of those sweaty sex scenes at all. You don't even have to have a sex scene at all. If you want one, fine, if you don't, that's fine also. And, if you do, you can create it any way you feel comfortable with and in the best way you feel it serves the story. Myself (and I'm like lots of readers, I think), whenever I encounter them, usually I just skip over 'em. Most are boring. It's virtually impossible to write a truly original or creative one any longer. Just don't feel you have to have one to "sell" your book. Not true at all. They're not obligatory in the least.
Hope that helps!
Here's something you might want to look at to see how a successful author writes a terrific novel where all through it there are obvious fireworks between two characters and never once do they do the nasty and yet it works as a powerful romance without them sweating and moaning in some Lady Chatterly sex scene. Check out Sandra Ruttan's Suspicious Circumstances. Seeing how this wonderful writer opted to answer for herself your very question and not include what some feel to be that obligatory sex scene will be illuminating, I think.