Adele wrote this for Simon Konecki, her longtime partner and the father of her son, Angelo. "It was sort of about a relationship suddenly getting really, really serious," she told Rolling Stone, "and then getting a bit frightened by it, and then realizing that, 'I think this must be right. This is the relationship that I want to be in for as long as I can possibly be in it.'"
The song is one of three 25 tracks that Adele penned with Greg Kurstin. The American producer also collaborated with the English singer on "Hello" and "Million Years Ago."
Adele expanded on the song's meaning to The New York Times. "It's about making a relationship work, about wanting to make a relationship work," she said. "All relationships are up and down, and that's part of a relationship - the tapestry of it and the muddiness of it. That's part of it, and that's as thrilling for me as the kicks I used to get out of a relationship falling apart. Overcoming those things - I think they make me feel powerful. They make me feel loved by him and make me love him more when we overcome stuff. I would much rather do that than just sit in the dark."
Amalia from CaliforniaThe Mirror ran a story in November 2015, which was about a week before Adele beautifully performed this song on the Tonight Show with Jimmy Fallon. Adele was quoted in the article as saying this about the song: "'Water Under The Bridge' is more like, I'm waiting for him to be horrible but I don't think he's gonna be, waiting for the relationship to end. This is the relationship now that I'm gonna be in. It was quite a ground-breaking moment."