According to The Mirror, the rugby player's fanatical female following "got a bit too much" for the 30-year-old. Brook's spokesperson confirmed that she was "taking a break" from the sports star earlier this month.
"Danny is a young, good-looking sports star and he couldn't help women throwing themselves at him. But it got a bit too much for Kelly," said a source.
"It was certainly one of the factors she took into consideration when they both decided to call it a day. She will not miss all that worry for one minute. It was quite relentless.
"Danny put himself in unwise situations where women could take advantage, and that was a concern."
Following their split, Brook has been spotted with Glee star Matthew Morrison, while Cipriani has been pictured with 90210's Jessica Lowndes and actress Jasmine Waltz.