TV presenter Caroline Flack decided to dumper her boyfriend after he was seen partying with 'Glee' actress Dianna Agron, an insider has revealed.

Caroline - who is currently appearing on the BBC reality TV show 'Strictly Come Dancing' - learned that her boyfriend Jack Street and 28-year-old 'Glee' star Dianna had been spending time together in America through friends, which prompted a huge row and the end of their 18-month romance.

Caroline Flack dumped her boyfriend after her was seen partying with Dianna Agron.

A source close to her said: "She has really been suffering but is putting on a brave face for the cameras.

"It was hard for her to find out about Dianna - especially as Jack was the man she thought she was going to marry."

However, the insider explained that still being involved with 'Strictly' has helped Caroline, 35, to take her mind off the issue.

The source said: "Their split was a painful decision and has put a massive strain on the whole Strictly process for her.

Dianna Agron caused split between Caroline Flack and her boyfriend Jack Street

"But having to concentrate on eight-hour rehearsals every day is helping take her mind off things.

"She is just getting on with it, like everyone else who has been in the same situation has had to do." sh

Last week, Jack, 27, sent a good luck message to Caroline - who's previously dated Harry Styles - via Twitter, which prompted a sarcastic reply.

She said: "Easing your guilt? Fill yourself with glee Jack."