I hear ya! It's been about a month for me. We are still living under the same roof. Friday night I came home after drinking wine at a friends house, and was so tempted to go upstairs where he is staying in the spare room. I stopped myself and was very proud. I made the mistake of doing that after the first week when he told me he wants a separation. That night the sex was incredible. I know, probably TMI.
All I can say is that his excuse for leaving is not lack of sex...the past 2 years has been the best in all of our marriage of 18 years. I just don't get it.
I am going to miss it. He is out looking at a place now.