I first heard this song purely by accident due to a mistake by the co-hosts on "Sounds of Japan". They were supposed to have played Mariya Takeuchi's "Fushigi na Peach Pie", but instead they put on this 45".
Years and years ago when I was back in high school, I used to listen to a radio program called "The Dr. Demento Show" which featured a whole bunch of bizarre oddities such as William Shatner's deathless cover of "Lucy In The Sky With Diamonds". The good doctor also ran a classic radio feature called "The Bickersons" starring Don Ameche and Frances Langford as a (barely) married couple locked in eternal hilarious argument.
Written and composed by Ben Sasaki（佐々木勉）, "San Nen-me no Uwaki" gradually became a huge hit as it stayed at No. 1 for about a month between December 1982 and January 1983. It ended 1982 as the 96th-ranked single but a year later it was the 12th-ranked song of the year. In terms of sales, the record sold over 700,000 copies. Methinks the lyrics may have hit a fairly sensitive and knowing chord amongst the population which would explain its popularity, but it was also for that reason that Hiroshi & Kibo didn't get invited onto the Kohaku Utagassen. I guess NHK figured that a song about marital discord wouldn't have set the right tone on the program. NHK's loss. The above video, by the way, has Hiroshi, but his partner is none other than Rumiko Koyanagi（小柳ルミ子）.
As for the two singers themselves, Hiroshi is Hiroshi Kurosawa（黒沢博） who was a guitarist and vocalist for the Group Sounds band Takeshi Terauchi and Bunnies（寺内タケシとバニーズ）. Kibo is Kiyoko Yamada（山田喜代子） who came up from Shizuoka Prefecture up to the nation's capital and spent 6 years there working before her debut, using that time for voice training. The pair ended up releasing 4 singles altogether during their time in 1982 and 1983 with the 2nd single being a sequel of sorts to their hit debut single titled "Go Nen-me no Hakyoku"（５年目の破局...The 5th Year of the Split）.