His last official partner was Bambou. In 1986, they had a son, Lucien, known as Lulu. In 2010, Lise Lévitzky published a book called Lise et Lulu which raises the possibility of Gainsbourg being bisexual. In 2017, Constance Meyer published a book titled La jeune fille et Gainsbourg, in which she reveals that she had a love affair with the musician during his last years, which began in 1985 when, then aged 16, she sent him a love letter.
He would show up drunk and unshaven on stage: in April 1986, on Michel Drucker's live Saturday evening television show Champs-Élysées, with the American singer Whitney Houston, he objected to Drucker's translating his comments to Houston and in English stated: "I said, I want to fuck her"—Drucker, utterly embarrassed, insisted that this meant "He says you are great..." That same year, in another talk show interview, he appeared alongside Catherine Ringer, the well-known singer from Les Rita Mitsouko. Gainsbourg spat out at her, "You're nothing but a filthy whore" to which Mitsouko replied, "look at you, you're just a bitter old alcoholic...you've become a disgusting old parasite."