Oliver Barrett IV, heir of an American upper-class East Coast family, attends Harvard College where he plays ice hockey. He meets Jennifer "Jenny" Cavilleri, a quick-witted, working-class Radcliffe College student of classical music; they fall in love despite their differences.
Oliver is upset that he does not figure in Jenny's plans to study in Paris. She accepts his marriage proposal and he takes her to the Barrett mansion to meet his parents, who are judgmental and unimpressed. Oliver's father says he will cut him off financially if he marries Jenny, but after graduation they marry, nonetheless.
Jenny works as a teacher but without his father's financial support, the couple struggle to pay Oliver's way through Harvard Law School. Oliver graduates third in his class and takes a position at a respectable New York City law firm. They are ready to start a family but fail to conceive. After many tests Oliver is told that Jenny is terminally ill.
Oliver attempts to continue as normal without telling Jenny of her condition, but she confronts her doctor and finds out the truth. Oliver buys tickets to Paris, but she declines to go, wanting only to spend time with him. Oliver seeks money from his estranged father to pay for Jenny's cancer therapy. His father asks if he has "gotten a girl in trouble". Oliver says yes, and his father writes a check.
Jenny makes funeral arrangements with her father from her hospital bed. She tells Oliver to not blame himself, insisting that he never held her back from music and it was worth it for the love they shared. Jenny's last wish is for Oliver to embrace her tightly as she dies.
A grief-stricken Oliver leaves the hospital and he sees his father outside, who has rushed to New York City from Massachusetts to offer his help after learning about Jenny's condition. Oliver tells him, "Jenny's dead," and his father says "I'm sorry," to which Oliver responds, "Love– Love means never having to say you're sorry", something that Jenny had said to him earlier. Oliver walks alone to the open air ice rink, where Jenny had watched him skate the day she was hospitalized.