Completely forgot that I heard this old chestnut by Mieko Nishijima（西島三重子）on "Sounds of Japan" long ago. Nishijima has often done a number of lilting countryside folk ballads although one of her most famous songs was "Gin Lime"（ジンライム）, a 70s City Pop/Mood Kayo standard with Mancini-level aspirations which definitely fits the atmosphere of a hotel top bar.
But then, she has also crafted these other types of ballads which take things closer to the city but have a much more old-fashioned bent to them thanks to some lush strings. "Jealousy" is one of those examples that I've often equated with Nishijima who composed it. Kenji Kadoya（門谷憲二）wrote the lyrics about an old flame or didn't-quite-reach-romantic-potential friend who comes to see the protagonist to tell him the good news that she's found a new guy. Meanwhile the sad hero is mightily biting his tongue at realizing that he may have lost the love of his life since he wants to keep her happy. I guess this would be the ultimate in bittersweet balladry.
"Jealousy" was a track on Nishijima's 7th album from 1982, "Image".