July 3, 2012— -- Whatever is behind Katie Holmes' decision to divorce husband Tom Cruise and seek full custody of their daughter, Suri, the 6-year-old girl will likely be the one most affected by the proceedings in the weeks to come.
"I think it will be absolutely traumatic," clinical psychologist Judy Kuriansky, also known as Dr. Judy from her radio show, told ABCNews.com. "She's been doted on, absolutely indulged, by both her parents. But they come as a packaged team to her, and splitting them will be very traumatic. I suspect she will go through a lot of acting out."
Reps for Holmes, 33, and Cruise, who turned 50 today, did not immediately respond to ABCNews.com's requests for comment. In previous statements, however, both stars have emphasized they were keeping the children's interests -- including those of Suri's half-siblings, Connor and Isabella -- at heart.
In a statement, New Jersey divorce attorney Jonathan W. Wolfe, who is representing Holmes in the divorce, said, "This is a personal and private matter for Katie and her family. Katie's primary concern remains, as it always has been, her daughter's best interest."
A spokeswoman for Cruise said, "Kate has filed for divorce, and Tom is deeply saddened and is concentrating on his three children. Please allow them their privacy to work this out."
Privacy may be the reason Holmes filed for divorce in New York, where divorce files are sealed from the public.
Nonetheless, it will be difficult for Holmes to shield Suri completely from the white-hot glare of the media, which has already documented Suri's every development, from holding on to her bottle and pacifier well past toddlerhood to her expensive designer wardrobe. Moreover, it will be nearly impossible for Suri to avoid seeing her parents' divorce splashed across magazines and newspapers.
"This isn't going to end any time soon," Us Weekly reporter Jennifer Peros told ABCNews.com. "Things can get really messy."
Little Suri isn't the only one likely to suffer the fallout of her parents' divorce, though. Cruise's two other children, Connor Cruise, 17, and Isabella Cruise, 19, with second wife Nicole Kidman, moved in with Cruise and Holmes, as part of a shared custody arrangement, after the two married five years ago, following a year-long whirlwind courtship.
"This is obviously the second time they have to deal with this," Peros said.
A close confidant of Connor told the magazine that Connor is "devastated." "Connor got really close to Katie and Suri. He's been in Iceland with Tom. Connor is definitely taking it hard," Peros said.
Peros said Isabella appears to be less affected, according to the magazine's source. "Bella has somewhat distanced herself from Katie and Tom," Peros said. "She's kind of rebelling in some ways. Any teenage girl with a stepmother is going to have differences."
As for the differences between Cruise and Holmes that have led to their divorce, much of the speculation centers on Cruise's religion, Scientology. Holmes seemed to embrace Scientology early on in their relationship, and even had a Scientology ceremony at their wedding. Now, she has petitioned for full custody of their daughter.
Kuriansky said the actress has an uphill battle.
"Seeking full custody is a huge move," she said. "Legally and emotionally, you have to have a lot of strength to go up against Tom Cruise, the movie star."
But Holmes has marshalled her forces, including adding a second divorce attorney, Allan E. Mayefsky, who represented model Christie Brinkley in her divorces. And she also has her father, who is a divorce attorney in Ohio.
Holmes may have been planning the split for some time. She reportedly spent much of her time in the past year in New York and obtained her own apartment in the Chelsea neighborhood in the past month.
While Holmes likely gains public sympathy with the reports that she may be divorcing out of a desire to protect her daughter, Kuriansky believes the split could also been driven by the actress's own needs.
"She started out with this fantasy of him, her dream as a little girl of marrying Tom Cruise, but the bubble has been burst," said Kuriansky, author of "The Complete Idiot's Guide to Healthy Relationships."
"This is about her as a mom, a wife, an actress and a woman stepping into her own," Kuriansky said.