One Chance

You didn't know what happened to the both of you. One day, you were both happy, and the next he's mumbling, saying that maybe, you two weren't gonna work out. And that was the spark that started the fire that would swallow you whole. It just hadn't gotten to you yet. Until now. Now, the memories of his fond look scanning your face and his shitty but hilarious puns make your chest ache with unbridled longing. Oh, how you missed him. The feeling brought up something you had read, how somebody speculated that you had only one soulmate. One chance. You felt like you fucked it up too badly to fix.Basically, Reader and Sans have broken up and after a suggestion from Undyne goes awry, you're both left to fix what you fucked up. Mentions of sex but no outright smut. There's a mention of non-con if you squint.