The former Home and Away actress, who has three children Mia, Cruz and Ava with Lleyton, is said to be upset at his potential return to the tennis circuit.
A source who identified themselves as a friend of Bec told Woman's Day magazine: "Bec sees it as a real betrayal. She had already started planning their new life back home in Australia when Lleyton decided to delay his retirement once again, this time to chase Olympic gold at the London games in August."
She is also alleged to have been "burned" by Lleyton "deliberately" hiding his most recent injury from her, especially as he told his parents Glynn and Cherilyn about the extent of his pain.
The source claimed that Bec and Lleyton almost split up when they were newlyweds because "his parents had the prime roles in his life and decision-making", adding: "He resented having to communicate with this person who had just become his wife.
"Like now, they never had fights, but just suffered along in silence when times were tough - and that sort of pressure kills Bec as she's bubbly and up-front, and what's happening now is pushing her to the edge.
"There was a very real chance they would split back then and I think she is struggling once again."
> Bec Hewitt 'happy with who and where she is'
> Lleyton Hewitt pays tribute to "beautiful" wife Bec