While Satoru was visiting your grave, he decided to jokingly bring a wedding ring with, and he learned a few vows.

“With this hand, I will lift your sorrows, your cup, will never be empty, for I, will be your wine, with this candle, I will light your way in darkness! And with this ring, I ask you to be mine,” he softly spoke before he placed the ring onto a supposed branch like finger, he sighed with a mutter, thats when your hand erupted from the ground, obviously it was skeletal like.