"I think there is a common misconception that (particularly) men are likely to be commitment-phobic or to exercise cold feet because of fears of intimacy," said Jerrold Lee Shaprio, professor of counseling psychology at Santa Clara University in California.
"What is more likely is that the true underlying fear is not of committing, but of committing and being abandoned or rejected while emotionally vulnerable."
Anxiety does seem to be higher in males, he said.
Englishman Steven Wheatley found the love of his life -- American Shannon Woodward -- on the U.S.-U.K. dating website called I Love Your Accent.
They scheduled their wedding for April 29, the same day as the royal couple.
"It's put the extra pressure on," said Wheatley, 40, who works in banking. "I thought it would be our day... It didn't gel that we would be overshadowed by Prince William... Everyone else will be glued to the television set watching someone else's wedding."
The pair will marry in Naples, Fla., and and they still don't know on which side of the pond they will live as a married couple.
Woodward admits she has the jitters, "big time."
"This was supposed to be my day," she said. "Now there are two people who are more important than me and they don't even live here. The English pub in Naples is doing a whole production in aid of their wedding!"
"I do have a little feeling of dread, rather than nerves," said Wheatley, though he has no doubts about his fiancee. "Was this a wise move?"
It's never too late to back out, according to Anne Milford, author of "How To Not Marry the Wrong Guy."
"I am stunned to this day how many women knew they were marrying the wrong guy as they were walking down the aisle," she said. "It happens all the time...It's hard to find women who called off their wedding."
Milford, 47, says she is now happily married to the right man, but she left her fiance at the age of 28, just months before the wedding.
"The age of 30 looks like a deadline for women, and it's not necessarily to have babies," she said. "It's the end of a decade and there is family pressure -- who are you dating. Your friends are all dating."
"A lot of women say they have been in a relationship with a guy and have been dating for a couple of years and like him. Deep down, they know they have invested too much time on this relationship and they don't want to back out and they think no one better will come along."
Nerves about the wedding day -- party planning details, if your uncle will get drunk at the wedding or if a divorced parent will behave himself -- are in natural, she said.
"But when you are having doubts about the relationship -- he has a hard time keeping a job down or spends too much money or drinks too much or we fight too much, that's a problem," she said. "So many women get caught up in canceling the party. What they need to do is cancel the relationship."
Months before the wedding, Milford mustered the courage to tell her mother and she knew that had made her decision final. "All you need is someone to give you permission in that ah-ha moment," she said.
"I remember the hearing the story of Princess Diana wanting out of the wedding and her sisters talked her out of it," she said. "In London this week, Kate and William's faces are on all the plates and coins. When Princess Diana expressed her doubts, they said, 'It's too late -- your face is already on the towels."
But the chances of Kate leaving William at the altar are slim -- 1,000 to 1, according to Bodog.com, the world's largest Internet bookmaker.
Even Lisa Libertini, who said she is more stressed out than Kate, working 50-hour days, six days a week to pull off her April 29 wedding, said with a good man, it's survivable.
"I think this past month has put so much stress on me," she said. "He's the guy. He gets a suit and shows up, and I am the one who does all the details.
"But I think that if he can stand me through probably the most stressful times of our lives and he can constantly calm me down and say, 'I love you," this will work out."