I'm an atheist, so I believe that life without our physical bodies is impossible. So my answer to your question is yes: our physical existence is the source of all suffering. However, it's also the source of all happiness, all thought, and also all dreams you may have. You can't stay in a dream state forever. You need to keep yourself going, or else you will stop existing. No more happy dreams for you.
It would be a lot easier if we were just thought. But we aren't. You're going to have to live with that (or die).
