While the title of this songs sets up the expectation that it’s about a relationship that’s over, the opposite is actually the case. Adele confirmed in her Rolling Stone cover story that it’s about her relationship with Simon Konecki, the father of her son Angelo, whom she’s since married.

It was sort of about a relationship suddenly getting really, really serious, 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.’

She also told Zane Lowe on Beats 1:

‘Water Under The Bridge’ is more like, I’m waiting for him to be horrible but I don’t think he’s going to be—waiting for the relationship to end, this is the relationship now that I’m going to be in. It was quite a ground-breaking moment.

Adele performed this song on The Tonight Show with Jimmy Fallon on November 25, 2015.

On November 1, 2016, it was confirmed by Billboard that “Water Under the Bridge” would be the fourth single released from 25.