But sports psychologists question whether the Simpson jinx is more than just typical superstition -- of which there is a great deal in professional sports.
"The first two games that [Simpson] was there Romo played great," said sports psychologist Jonathon Katz. "But because he did poorly and she was in the stands now everyone is saying it's her fault. It's not logical or rational -- people often look for a reason as to why people have performed [a certain way]."
Katz added that while he's not convinced Simpson was a jinx, she certainly was an unneeded distraction.
"It's less about superstition and it's more about a distraction," said Katz, who has been a consultant to many professional sports teams, including the New Jersey Nets and the Chicago White Sox. "Coaches will always tell athletes to do whatever they want to relax during a bye week, but when something becomes a distraction, it's a big problem for teams, especially toward the playoffs."
"It's not always what takes place that's the problem, but what happens as a result of it," said Katz, who added that the entire team was affected by the rumored relationship, fielding questions about their vacation plans rather than Dallas' game plan.
In a tearful press conference following Dallas' loss Sunday, Romo stood up for himself -- and his alleged new girlfriend.
"I don't live with regrets," Romo said. "I'm content in my own skin. If I try to be a good person and I'm strong enough in my faith, then I feel like I'm doing it the right way."