The Time Keeper by Mitch Albom
Quickie spoiler: Victor dies and leaves tuition money to Sarah, who eventually becomes a doctor; she discovers a cure for the disease that killed Victor.
Dor is a man who exists “at the dawn of man’s history.” He’s married to his childhood sweetheart, Alli. But when Alli is about to die from a mysterious, contagious disease, Dor attempts to stop time, an effort that finds him in a cave with an old man. The old man grants Dor his wish; as a result, Dor becomes Father Time, an existence he maintains into the present.
Dor finds himself with two charges: seventeen-year-old Sarah Lemon and billionaire octogenarian Victor Delamonte. After being publicly rejected by her crush on social media, Sarah wants to end her own life, while the terminally ill Victor wants to prolong his via cryogenics. As the two try to follow through on their mission, Dor intervenes and shows each of them what life would be like if they succeeded. While Sarah’s crush shows no remorse, her mother is devastated, blaming herself for her daughter’s suicide. Victor finds himself a few hundred years in the future, barely alive and existing in a tube, his wealth completely gone.
Dor is freed from his sentence as Father Time and reunites with Alli; he catches her illness and they die in each other’s arms. After seeing their futures, Sarah and Victor abort their plans. Victor passes away, but leaves Sarah money for an Ivy League education, which helps her become a doctor and find a cure for the disease from which he died.