1. My friend who cheated on his gf of 1.5 yes broke up with her because he "fell out of love." 6 months later after some LC and NC he broke down in tears and admitted he cheated but she took him back. Unfortunately, he had not worked out some issues and got cold feet again ("not in love") and she broke up with him after another 2 months.
Next 3 are potentially successful reconciliations, albeit works in progress.
2. My friend who had a pretty mutual break up with gf heard from her recently after about 4 years asking him out for a coffee. He had an LTR between then and I think he's way more prepared for whatever happens next.
3. Friend broke up with his gf of 1.5 yes, fell out of love again, had GIGS. She played the jealousy card on him super hard and basically got him to start pining for her. They've been meeting up sporadically every year with their own relationships in between and I think those two haven't ended their story yet.
4. My friend is in the process of meeting up with an ex gf of 4 years. He had broken up with her twice (case of cold feet/parent pressure,) she finally broke up with him and they went NC for about 9 months. They're meeting up soon.
I've got plenty more I can post if you guys want. In most of these, it was mainly either a technicality (LD) or a fizzlin out / loss of feelings (one of which included infertility.) I'll update on whether the last 3 end in reconciliation.
But,as far as any hard rules on whether to go complete in NC or what, it's much better to judge each situation individually. However, a good length of NC seems necessary at one point or another.