The 35-year-old Palm Beach socialite did not like the manual labor asked of patients at the famed Rancho Mirage, Calif., center, such as chores, a source said.
"Brooke didn't tell anyone, including her lawyer, that she had left Betty Ford," an insider close to the situation told Radar.
"Brooke hated Betty Ford because she was required to do daily chores, which she resented. She complained that Betty Ford was just too hard. Betty Ford is hardcore and Brooke just doesn't respond well in situations where she can't call the shots."
But her abrupt move to leave the facility and enroll in a clinic in San Juan Capistrano, Calif. -- her 21st stint in rehab -- could have severe consequences in her bid to regain custody of her four-year-old twins with the Anger Management star, Bob and Max.
On Tuesday, there will be a routine hearing in the ongoing custody battle, where the judge is expected to grill Mueller's lawyer about leaving Betty Ford.
"This could have a serious impact on Brooke's bid to get custody of the twins. Brooke just doesn't seem to be taking get sober that seriously," the source said.
"Her doctors at Betty Ford advised her not to leave, but she did anyway. Her counselors will be submitting an extensive report about Brooke's time at Betty Ford and it won't be glowing, that is for sure."
Neither Sheen or the twins' guardian, the actor's second ex-wife, Denise Richards, are expected to be in court for the hearing.
"The boys have spent more time with Denise than with their own biological mother for the last nine months. The boys are a part of Denise’s family and they are extremely happy in her care,” a source told us.
Though Mueller enrolled in Betty Ford voluntarily, it wasn't until after child protective services took Bob and Max from her and she was placed on an involuntary psychiatric hold at the UCLA Medical Center.