Accentuate the positive - you aren't losing a teenager, you're gaining a bathroom! And plenty of hot water. Clean towels. The food you like in the fridge (food in the fridge, period!). The television show you like to watch. You get the idea.
If you think you want to spend as much time as possible with your teenager - after all, he'll be gone soon - consider that your teenager probably wants to spend less time with you. That's healthy. "Disengaging is a two-way street, and parents who don't do their part end up having more of a problem with their adult children," warns Sheri Stritof, coauthor of The Everything Great Marriage Book.
Instead, focus on your friends and start spending more time with your partner. The kids may be leaving, but you'll be spending the rest of your life (you hope) with your partner. The greatest predictor of marital success is the level of friendship, Arp says, and one way to build that friendship is by going out on dates. So take dance lessons. Go out to dinner with another couple (this will help you talk about things other than the kids). Plan a parents-only vacation. Working on the senior prom with a group of other moms helped Clare Chaney let go of her son, and she enjoyed the bonds formed with other senior parents.