Feeds
Rex Features
The DJ was unhappy with Harding's close relationship with backing dancer Jackson Williams, reports The Mirror.
"It is a really sad situation but Tom has definitely walked out on Sarah," said a source.
"Sarah was constantly linked with other men and, even though it's always been perfectly innocent, he found it tough."
Harding is apparently "devastated" by the break-up, but is being reassured and looked after by her bandmates.
"Sarah's getting chirpier by the day," added the source. "The rest of the girls have been great. They're sad about the split but are making sure Sarah keeps her chin up."
