There's a Kickstarter going right now for the LoveSync, which is a pair of buttons, one for you and one for your partner. And you're supposed to press your button whenever you're in the mood to get-it-on.
If your partner has also pushed their button, then your button starts glowing green, and you know you're both in the mood.
But if they haven't pushed theirs, then you know they're not. And since they won't know that you pressed your button, it's not like they're rejecting you . . . they just happen to not be in the mood at that moment.
If you're interested, it's $44 for a set of LoveSync buttons, and they're set to ship in August . . . IF the Kickstarter hits its target. Right now it's only about one-third of the way to its $7,500 goal.