This wasn't a love scene per se, but I still remember in
Witness (that Amish movie with Harrison Ford and Kelly McGillis), there was a really sexy scene.
She is taking a bath in one of those old fashioned wash basin tubs and the door is kind of ajar....she looks up and sees Harrison Ford watching her in the mirror through the door's opening.
And she just stares back and doesn't cover herself.
You can just FEEL the sexual tension! And while they do end up smooching late in the movie, that's as sexy-sexy as it gets.
Sometimes the sexiest scenes are no sex at all!!