Please recommend a novel. In the story, the female protagonist was very thin at first, but later became fat because of pregnancy and abortion. The male and female protagonists grew up together.

Find a novel in which the male and female leads are childhood sweethearts, and the male lead's father is their physics teacher. After the female and male leads broke up in high school or university, they got pregnant, and it seemed to be an eccentric pregnancy. After the abortion, they slowly became fat, and it was super fat. Later, in university, the male lead found her and reconciled with her.