The Amulet — Michael B. Dodd

In the year 2125, a man's humdrum life within a dystopian world is shaken when a time traveler from the future gives him the opportunity to journey into the past and change his world's calamitous fortune. Regrettably, his means of travel would allow for a trip in only one direction. While the prospect of curing his planet's present-day ills is appealing to him, it would mean leaving forever the woman he loves. His choices come down to spending the rest of a tedious existence with a woman he has come to adore or venturing 60 years into the past in order to remake her world and give her a chance at a more full and meaningful life.