My sister broke up with her ex who she 'dated' for around a year just after high school over something trivial. Think he dumped her.
Went on to have a four or five (?) year relationship with the father of my nephew, living together - and if I remember rightly briefly got engaged. The relationship was rocky to say the least.
She randomly bumped into her ex on a night out and promptly broke up with her then fiance (?) and got back together with her ex. They have been together now for around ten years and live together, happy as Larry. Completely NC the whole time they were apart (not sure how long that was 5-7 years maybe?).
Pretty sure they also split up for a week or so, possibly less at one point if I remember rightly.
Myself... of seven from what I would call 'serious' relationships... all but one have come back, but I chose not to reconcile with any of them. In all cases I have been the dumpee.
Only two of note:
Both BF nos. 1 and 2 mirrored each other's behaviour... (on separate occasions) each left me for another girl around six months into each relationship... after around two months they each dumped their new girls and asked for another chance... initially I took each of them back and I dated each for a total of five years each. At four years, each of them then broke it off/on/off/on for a number of months (too young, wanted to do other things, etc,etc.), until the last time they both asked for another chance after a few weeks NC... where I had had enough of each of them and did not reconcile.
Both never had another serious relationship until bf no. 1 married ten years after we broke up (but would leave his wife tomorrow for me) and bf no. 2 died without being in another LTR (I hadn't seen him for over ten years at that point).
I think this thread is brilliant... however, while we all wish and hope for the fairytale ending, the morale of the story is DO NOT put your life on hold for anyone. There is hope, but more importantly, there is YOU.