I personally know of two separated (DBer) couples who got back together and have read about a couple more. It seems that is is usually the ones who have been only separated a short time.
H and I were S for nearly 2 years before we reconciled... I know of one couple that remarried after 5 D'ed...another that was S for over 10 yrs...and another that have been D'ed for 12 yrs and are now considering remarriage... My H said if we had gotten D'ed we very possibley would have remarried too...
It happens...but not 50% time...that is pretty high odds!