In longing, one can “repine over” something (“repining over her lost past”), or one can “pine for” something. The two words, used thus, mean close to the same thing, but not exactly. Pining refers to intense longing for what one once knew. Repine adds an element of discontent to any longing—an element carried over from its sense “to feel or express dejection or discontent,” which has been in use since the 16th century. Washington Irving used the earlier sense in his 1820 work The Sketch Book: “Through the long and weary day he repines at his unhappy lot.” Pine and repine are from Old English pīnian (“to suffer”) and probably ultimately from Latin poena (“punishment”). Poena also gave us pain.

Examples

“All his journeys were ruggedly performed; for he was always steadfast in a purpose of saving money for Emily’s sake, when she should be found. In all this long pursuit, I never heard him repine; I never heard him say he was fatigued, or out of heart.” — Charles Dickens, David Copperfield, 1850

“For about half an hour I felt quite low in spirits because of Charley Heywood’s unannounced departure, but I am not one to repine over matters that can’t be helped.” — Dee Brown, Conspiracy of Knaves, 1987