A has 30 days left until they are shipped overseas in the military.

In those 30 days B has to spend as much time as possible with B and starts making a scrapbook to look back on when A is away.

Five years later B is showing their little girl the scrapbook, the last memory of her daddy before he was killed overseas.

(B was pregnant during the 30 days or had a baby before then. Or they adopted before. Would prefer an mpreg though)