Ditto, FF. I enjoy riding with friends but I need some me time. Especially since my outdoor rides have been limited since an injury earlier this year.
However it's a 12 mile ride just to meet up with friends for group rides, so in practice I still get 24 solo miles. And it's a fairly challenging route with some good segments. Alas, a younger cyclist friend who lives nearby has beaten all my best times since he got serious about riding this year. Darned kids.