Realize that in any good company, there will always be an expectation that people eventually move along to other opportunities. Don't feel any shame about going back.
In any good company that has been around awhile, there is doubtlessly a number of people that have left the company and come back again under much better circumstances (as in worked another job for a while and then came back). At the company I work for, there are a handful of people that have left the company and come back again over 2 or 3 times over the years.