The first nice thing about your kids moving out:
1. You can make noise in the bedroom.
Well? This is important.
2. You can flit about the house half-dressed after your bath and while dressing.
There are some sorrows you only feel when you actually think about something sad, and other sorrows that you feel underneath whatever else is going on in your life. I’m not sure which this is; probably a bit of both. And along with this sense of “letting go” of the old life is also some relief (oh how the grocery bill will dwindle!) and gladness (oh how good this will be for him!) and a knowing that all is as it ought to be.