Great read.
An instance which I can think of was a few years ago. My girlfriend at the time was very close to her group of friend/co-workers, and I also got quite well along with them, even if they were totally different from the people I'd usually hang around with. My less flexible girlfriend, however, really didn't get along with my friends. So instead of dumping my friends to get solely in her group, I kind of split my life into two, for two group of very different people, with which I acted totaly differently than with the other group.
As for an online secret life, well, I'm a MMORPG fiend.. so a second life which consists of slaying orcs is hardly shocking, I'd think
