I actually kept a few of my favourites who haven't been on for years or many months.
Not necessarily for the hope, they will come back but more of the "good memories", just to see their name, and do not want to forget about them.
But it is also a small chance and hope they will decide to come back, so I don't want to forget or miss them coming online if they do make a comeback.
On my alt account I have most of them, on my main account I have 2 which I really enjoyed and had amazing times with, etc
(I follow about 20 women total, including the ones inactive)