Helppp

Looking for a bl manhwa where the mc is a substitute for the white moonlight(first love) and leaves after realizing he's the "inferior copy", he goes to a rural town. he pays someone to guide him and picked a (young) guide whose grandmother has Alzheimer's and mistakes mc for his grandchild. Then the guide dies in a car accident (while touring mc around?) And the mc takes the guides name and takes care of the grandma