Does or has anyone felt a feeling of restlessness after they separated from active duty?

Everyone has made some great points that I agree with. I just want to add my two cents because of one major point. This feeling of isolation or restlessness you feel never really goes away. I have been off active duty for five years now and just about everyday I ask myself what I can do to get that camaraderie and feeling of worth back. I don't regret my decision to separate (after living a dependent's life overseas it is something I personally did not want my family to deal with) it is just a nagging feeling due to the missed connections you make in military service. These types of sites, volunteering, staying in touch, etc. all might help to make it a little less apparent; but that feeling is always there.

I understand what you're feeling. I felt the same way for a while after retirement. A weekend at a lake with a cooler, rod and reel has been known to work wonders! If that's not your thing, take up a new hobby that has nothing to do with your former routine. It will never entirely go away (and I don't think that's necessarily a bad thing) because the military, for most of us, becomes a part of who we are, and who we will be for the rest of our lives.

Restlessness? Maybe, but it has gotten better over the past 22 years.
Uselessness? Absolutely, and it has gotten worse over the last 22 years.
The civilian world sucks. No sense of duty, honor, country. All the civilian world cares about is advancing their own agenda, regardless of who they destroy along the way.