Music industry insiders revealed the ballad is being viewed as a likely sequel to her Brit Award-winning heartbreak ballad Someone Like You.
The lyrics are thought to relate to meetings she had with the former love, who she wrote much of her second album 21 about.
In 2011 she told of her regret over their relationship, saying: “I don’t think I’ll ever forgive myself for not making my relationship with my ex on 21 work, because he’s the love of my life.”
She later admitted that the pair had reconciled and that they were “becoming friends again.”
While she has never revealed his identity, the person in question is widely assumed to be the photographer Alex Sturrock, who she dated for around a year in 2008 and 2009.
She was also linked with musician Slinky Sunbeam and DJ Ned Biggs around the same period.
A music industry insider revealed: “That one ad has changed everything for Adele.
“The talk over the last few months has been that the album won’t be able to live up to the hype, but just 33 words from one song has turned all of that thinking on its head.
“She’s written a sequel to Someone Like You, which is what everyone has wanted but no one believed she would do because she’s in a long-term relationship with a man who she has a child with.”
Sources say the song is definitely not about her partner of three-and-a-half years, who she has spent increasing time apart from as she endured a torturous period trying to finish her third album.
For months she even banned Simon from listening to any of the music, claiming she wanted it to “be a surprise for everyone”.
A source revealed: “This whole process is clearly going to be very difficult for Simon because she’s singing about the love of her life — and the reality is that it isn’t him.
“There are bound to be love songs on the album about Simon and Angelo, but it’s telling that the song she’s going to be selling the album on isn’t about him.”
