A scenario like that sits at the absolute extreme end of the betrayal spectrum, doesn't it? It's not just a simple affair; it's abandonment at the moment of greatest vulnerability, with the added, almost cruel, complication of twins. Survival isn't just about the romance but the woman's entire sense of self. Many stories use this as a brutal inciting incident for a revenge or comeback arc, where the heroine rebuilds a life so powerful that the ex's later regret is meaningless. The 'romance' that could follow wouldn't be a simple reunion. It would require a complete narrative demolition of the male lead. He'd need a redemption arc of epic proportions—genuine, sustained grovel, profound understanding of the trauma he caused (not just the cheating, but the medical and emotional peril of a twin pregnancy alone), and a total relinquishment of power. Even then, the emotional calculus is so skewed that many readers would reject any reconciliation outright. For me, the more satisfying narrative isn't the romance surviving, but the heroine surviving it. The 'romance' that eventually forms, if any, would be with someone entirely new who recognizes her strength, or a version of the ex so fundamentally changed he's practically a new character. The original bond is too poisoned.
I've seen attempts in some webnovels, but they often falter by rushing the forgiveness. The weight of twins—the symbol of double life, double responsibility he walked away from—makes the betrayal exponentially heavier. Any story that tries to mend this has to spend more time on her healing and independence than on his apologies. Otherwise, it feels emotionally dishonest, like the narrative is prioritizing a 'happy ending' over the character's earned peace.