If it feels like you're not connecting and that you're going through a purge, you probably are. People come and go in your life for all sorts of reasons. Just go with it and let it go.

I've had this friend from college study abroad days and one day he flaked out on paying me back for a NYE party ticket and just stopped picking up the phone,e tc. wtf right? haha.

Other people will leave for diff reasons and maybe no reason at all (on the surface).