The singer most associated with "Love Is Over" is Taiwanese singer Feifei Ouyang (欧陽菲菲) who had first started her career in 1967 in Taipei before coming to Japan in 1971. She became an instant hit with her first single there called "Ame no Midosuji"（雨の御堂筋...Rainy Midosuji), which sold more than a million records and earned Ouyang a Newcomers Prize at the 1971 Japan Record Awards. She also appeared the next year at the Kohaku Utagassen.
In 1979, Ouyang first sang "Love Is Over" as a B-side to another song which only sold 20,000 to 30,000 copies. However, it seemed that the singer never gave up on the ballad and by 1982, the song was re-released as the A-side, hitting the big time throughout 1983 and 1984. At the end of 1983, it had finally reached the top spot on the Oricon weekly charts and stayed there for 2 weeks. It became the 18th-ranked song of the year in 1984. Furthermore, in 1991, she finally performed the song at that year's Kohaku. By the way, the song was written and composed by Kaoru Ito （伊藤薫）.
In 1981, Ruiko Kurahashi（倉橋ルイ子） debuted with her album, "Without Sugar". On the album, she gave her own version of "Love Is Over"; it was similar in style to the Ouyang version in that it was recorded as a pop power ballad with Kurahashi actually openly sobbing near the end of the song. However, a later version was recorded in which the arrangement had been changed so that this newer rendition was done as a jazz ballad. In this case, it's just Ruiko's voice and a piano. This version can be found in a number of her BEST albums, but it seems like its first appearance was in the 1985 album, "Ballad wo Kaban ni Tsumete"(バラードをかばんにつめて....Put the Ballads in the Pouch).
Take a listen to both Ouyang and Kurahashi versions and tell me what you think. In any case, the song has been a popular one (for us older folks anyways) at the karaoke box.