There are times in every man's life when he just feels groggy and just wants to take some well deserved rest. During most of these long awaited alone times, your own temptress comes a long and spoils your quiet r&r.
Normally it would be an offer you couldn't refuse and you'd gladly bite the bait, but sometimes it does become taxing. For the most part, you're left in an awkward situation she lets you feel guilty over withholding sex. If she's not understanding, you've got more to face, expect there's more punishment than a week's worth of cold nights! There are more appropriate ways to turn down a sexual offer from your promiscuous partner.
You can try to divert her attention. Let her think of more important things she should handle that you know she likes. While she's away, you can let her indulge more into the other things that are keeping her. Remember to do this with caution, though. Generally, women know when you're trying to get the better of them. Once they feel that they're your own personal kinky escort for the night, nothing usually stops them. A woman is biologically predisposed to have longer sexual drives than men, but these come at less frequent times. When they do come along, diverting her focus will not be an easy job!
Another alternative would be to fake it. Come on, you're a guy, and one way or another you know that you're going to get aroused any minute. So might as well fake it along the way and make sure that you're "objective" about it. She's turned on, you can too, so why not? It saves you the trouble of explaining and being at fault for something that was well intended. However, if her sexual appetite does become unmanageable, you can persuade her to do more intimate things instead. Try opting out where you can cuddle, hug each other and maybe talk to her, and hope that it works until you both fall asleep.
Here's the trickiest thing you can do: be honest about what you feel. When all the signs are there once you open the door to your apartment and you see a cooked dinner, smell scented candles and see her dress up like a kinky escort, then you now where everything is heading. If you don't want to deal with her for the night, then sit her down and tell her you appreciate the effort. Nonetheless, explain to her gently that you're tired and it's best to postpone the night to some other day. That way, you'd be more open with your partner and avoid the mess to become any stickier. If she truly cares for you, she'll get it.
Rocket science has to be a lot easier compared to planning the right timing for sex! Although you do end up with loose ends, and maybe get thrown away to the couch for a night or two, the important thing is you get your much needed sleep! You can't please everyone all of the time, anyway.