If I waited on my husband to tell our adult son to move out, he'd probably still be living at home!
I bought a book by Alison Bottke (Setting Boundaries with Your Adult Children) and that really helped me get my thumbs out and make some changes like get the car keys back from our son and discuss his moving out. Fortunately he had already decided to move in with his girlfriend, but what I told my son was that our home is not Plan B should it not work out between him and the girlfriend. He was not happy, said "Thanks Mom for being so negative". As it turned out, he tried to pull a fast one over on the girlfriend and he almost had to find a Plan B. Maybe by knowing he couldn't come back here he decided to straighten his act out (for the moment anyway). He seems to be doing okay now.