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" is intense longing for what one once knew. "Repine" adds an element of discontent to any longing - an element carried over from its first sense ("to feel or express dejection or discontent"), which has been in use since the 16th century. (Washington Irving used the first 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 "pinian" ("to suffer") and probably ultimately from Latin poena ("punishment"). "Poena" also gave us our word pain.
Examples of repine in a Sentence
there is no use repining over a love that's been long lost