The Sun claims that the singer joined the DJ in Ibizia last week, in an attempt to salvage their relationship.
"Sarah and Tom had a huge bust-up and told each other the wedding is off," a source told the paper. "Although they've always managed to patch things up in the past, it's worse than anything they've gone through before.
"They've been fighting like cat and dog. Their relationship has been strained because he's been in Ibiza for the summer and Sarah was working here. They've always had a volatile relationship but this time it's far worse."
The insider added: "If they do get married, they both need to start living their lives differently — and that's not going to happen any time soon. It's a shame as they do really love each other but pals can't see how there can be a way back from this."