It's about an age gap couple, the older one died in a car accident trying to protect the younger one, the younger one got sent back to the past to when he was in his toddler age I think he was born in 2015 or something and his partner at the time is a vet. That's all I could remember, please help me find it I want to reread it
I'm looking for mangas that has very good world building with psychological aspects, some examples: The Promised Neverland, Girls' last tour and Made in Abyss
https://www.mangago.zone/read-manga/yabun_ni_kyuuketsu_shitsureishimasu/