“What does get married mean?”

A question my fiancé’s 3 y/o nephew asked me when he heard us talking about wedding planning. His mom is a single mom so I wanted to be sensitive when I answered this question—I just responded that “it just means that your uncle and I promise to love each other forever and ever.”

He’s going to be our ring bearor (which he’s done before) and I’m so excited. I love that kid so insanely much. I’m curious how others would’ve responded to that question though in an age-appropriate, circumstance-appropriate manner?