I started out with a single. I always had the intention of having 2, but when I tried to get him a friend, all he would do is call for me when I was away from him, and stay on me when I was around. He liked the other guy well enough, but was very happy with me. (Unfortunately, the 2nd glider I got had apparently fallen when he was a joey - before I got him, and because it was never noticed/treated, his internal organs didn't grow correctly, so he died in just a few weeks).
And, devastating to me, my first glider died because I trusted the wrong person to take care of him while I was on vacation (I had a little girl lined up to be his new friend, but he never got to meet Kira).
When I decided to keep Kira and Dakota's first joey, Pascal, I kept him as a single for a little over a year. We looked at females, but they never seemed to get along, not how I thought they should anyway (and no I didn't keep them for days or months, but had this feeling that it should a be love at first sight thing, and with Lili it pretty much was
). ANYWAY...with Pascal as a single, I have to admit it was a wonderful relationship and he would call me at night to come and sleep with me (during his 'rest' time). And was with me all during the day.
And now...I have a single because she cannot be introduced to my other gliders right now as a glider in each cage has had a Giardia recurrence.
She is so small and was so sick when we had the first outbreak that I will not put her at risk. That said, I have every intention of her being in one of the cages eventually...but it will still be a while to be sure the Giardia is gone. And she spends nearly every day for 11-12 hours with me and when she calls, she calls to me, not to the other gliders.
I always told people that it is ok to have a single for a while because it is a special relationship, BUT you have to spend all of your time with them and have tent time with them daily, etc., etc., etc. And, to always have the intention
of getting a glider, if for no other reason than the fact that things change in your life (illness, work, family, etc.) and if you don't feel you 'have the time for them' sometimes, they will always have each other. I have seen it so many times that people loose interest or thier lives change, I always felt better about joeys I had sold knowing they had each other no matter what.