Some people don't know how to relate to those outside their social group. They are familair only with interaction within that confinement. Can happen with groups other than Church as well.
For me, I left facebook -- and Ive not heard from any of my 'friends' cept maybe one or two who live local anyhow, in the 6+ months since I've been gone.
It's like i dropped off the face of the earth - even tho i call and email.