When Bullock -- America's sweetheart -- married the reformed bad boy and tattooed biker in 2005, they appeared to be an unlikely couple, but as the years passed, their relationship seemed stable and happy.
That changed a few weeks ago after tabloid reports that Bullock's husband reputedly had an affair with Michelle "Bombshell" McGee, a San Diego tattoo and fetish model who reportedly also worked as a stripper.
The reports were stunning, and came less than two weeks after Bullock's triumphant best actress Oscar win for her role in "The Blind Side."
Though Hollywood often seems like the center of the universe for infidelity allegations, the same drama plays out on a less public scale in homes across the country. But experts say there are ways to sniff out infidelity and, if it's found, how to deal with it most effectively.
Expert's Clues to Infidelity, What Happens After
According to therapist Bethany Marshall, there can be several clues when one partner may be having an affair.
Pervasive pattern of selfishness. Does he or she only worry about self-gratification?
Excessive secretiveness. Does he or she erase texts from his phone? Screen calls?
Sudden interest in his or her appearance. Is he or she suddenly working out and losing weight?
Renewed interest in sex or trying different sexual practices.
Isabel Gillies, an actress and author of a book on infidelity called "Happens Every Day," said that she had no idea when she was being cheated on.
"People are surprised that you don't know," Gillies said. "But I see a lot of people in these book groups and say 'Does anybody think that their husbands would cheat on them?' and everybody answers 'no.' It's just sad and it's important to look at both sides of the coin and try to see the other person as a whole."
If there is infidelity, Marshall said the next step is to determine what kind of problem the relationship is in.
"There's three types," she said. "There's the one-time colossal mistake with an otherwise good guy. There's a guy who cannot handle the marital stress. And then there's the guy who always wants narcissistic gratification."
Marriages can survive infidelity, Marshall said, but a few things have to happen first.
Offending party has to be sorry. "He [or she] has to be willing to repair the damage by showing remorse," Marshall said.
Admit the affair and why it happened. "If you can't articulate it, how can you fix it?" she said.
The offender must make a plan to fix the problem.
Gillies said repairing the relationship requires both parties, however.
"It's a complex situation," she said. "I think it's important also when somebody does something that's socially unacceptable like an affair. The person who has had the affair happen to them can sort of put a halo on and say, 'You did something really bad.' It's important for both partners to look at how they work together.
"One person can't be a devil and the other can't be an angel," she said.
Tattoo Model at Center of Scandal
McGee, the tattoo model with whom James allegedly had the affair, told In Touch Weekly magazine that she began an 11-month relationship with him while Bullock was filming the Oscar-winning "The Blind Side."
When she accepted the Oscar, she publicly thanked her husband. He had tears in his eyes.
Bullock has reportedly moved out of the Southern California home she shared with James. She also canceled her scheduled appearance at the London premiere of the movie, citing "unforeseen personal reasons."
Last week, James, who still wore his wedding ring, was photographed walking his three children to school -- without Bullock.
James released a statement taking responsibility for the couple's heartbreak:
"The vast majority of the allegations reported are untrue and unfounded. Beyond that, I will not dignify these private matters with any further public comment. There is only one person to blame for this whole situation, and that is me. It's because of my poor judgment that I deserve everything bad that is coming my way," he wrote.
He also asked for forgiveness.
"This has caused my wife and kids pain and embarrassment beyond comprehension and I am extremely saddened to have brought this on them," he wrote. "I am truly very sorry for the grief I have caused them. I hope one day they can find it in their hearts to forgive me."
Bullock's representative did not respond to requests for comment.
If the stories are true, this could be a sad ending to an unlikely fairy-tale romance.
She was "Miss Congeniality," a popular, well-paid Hollywood actress. He was a reformed bad boy turned successful businessman and reality TV star.
Despite predictions their union would fail, they appeared to have found domestic bliss in Los Angeles and Austin, Texas, raising James' three children from his two previous marriages.
Bullock even put her career on hold while helping to raise the children. She also got involved in James' custody battle with his porn star ex-wife over one of the children.
It is unclear how the reports of infidelity will affect Bullock's relationship with her husband's children.