You fell into the underground and met Toriel. You ended up living with her to stay safe and eventually developed feelings for her. One day you confess to her.

Toriel: Eh? Please surely you’re joking. How can you feel that way for an old lady like me?

You kept telling her it’s true and you eventually start dating. —————————- A year passes and you wake up to something good smelling in the kitchen. You go and see Toriel in her apron cooking.

Toriel: Oh good morning!