... to get a love interest instead of to save a kid. And if you make it about Joe and Sara finally uniting heading forward into the future, that's tonally a waaaaay different call than Joe realizing his life isn't as important as insuring (in his mind) the life of a child.

I had a similar issue as you the first time I saw it, but I'm not sure they could have ended it any other way. I still have the issue... but it didn't make me feel as iffy. He can't end up with the girl without distracting from the whole children-and-their-fates theme, so how else can the film end?