First, the two remained grateful to each other even after their breakup.
If two people remain grateful to each other when they break up, it's actually quite easy for their old flame to rekindle. This is because they are clearly still grateful for each other's companionship. However, if two people break up without any grace, filled with hatred and jealousy, then such a breakup is destined to never lead to a rekindling of their old flame. The foundation for a rekindling of an old flame lies in the attitude of the two people at the time of the breakup. If their attitudes towards the breakup are sincere and filled with gratitude, then even if they are both likely to remain single for many years, it's easy for their old flame to rekindle.
Second, the two remained in contact even after breaking up .
If two people remain connected after a breakup, and each still carries a trace of the other in their lives, such a breakup can easily lead to a rekindling of old feelings. Some people don't completely sever ties after a breakup; instead, they become even more aware of their unyielding love and longing for each other. Therefore, their reconciliation is simply a natural consequence.
Third, the two were unhappy after their breakup.
If both people are unhappy after a breakup, this is when they are most likely to rekindle their old flame. Some loves are sweet, touching, and unforgettable in the moment. Only after some loves have faded do we feel as if something is missing, and our lives and souls feel incomplete. Two people break up so they can each find happiness again. However, if, after finding new partners, their lives don't improve but instead become more miserable or repressed, then the sweet memories of their past love will resurface in the quiet of the night. Therefore, for two people who haven't found happiness after a breakup, rekindling their old flame is most likely.