
Basically, the 5 years in the current planet is 20 years in Astracell. Time passes by different.
From what it seems. His wife died five years ago and was born again. In five years, she came back as a 20 year old(because she grew up in Astracell time goes differently)
In her first life which she doesn’t remember, she grew up with ml.
It’s quite likely that the childhood sweetheart she remembers is just memory from her past life she subconsciously remembers.
Hope that helped.ヾ(☆▽☆)

I don’t get how the save artefact works?

Everytime the male lead goes back in time, his memory also resets to the time he came back to. Meaning he doesnt retain any memories after his last reset point. Everytime he loops back, he basically relies on instinct and muscle memory to slowly alter the future with very minor adjustments.
Geymafia says with the floppy disk, he should be able to remember his memories past his reset points so he can actually plan out his moves to change the future instead of being completely unaware
This looks VERY promising