When the wedding is over and the marriage begins, it can be challenging to stay true to your "I dos."

A 60 Minutes/Vanity Fair poll published Wednesday revealed exactly which vows men and women struggle most to keep, and the results show a noticeable gender divide.

"To be faithful" was the most popular choice among men, with 27 percent of men polled voting it the most difficult vow to keep. "For better or for worse" earned 23 percent of the men's votes, followed by "For richer, for poorer" with 18 percent and "In sickness and in health" with 17 percent.

Women, on the other hand, found "For better or for worse" the most challenging vow. Thirty-two percent of of the women polled thought this vow was the hardest to keep, while 25 percent chose "To be faithful," 16 percent chose "In sickness and in health" and 12 percent selected "For richer, for poorer."

The poll also found that 87 percent of those surveyed think good sex is "very" or "somewhat" important to a successful relationship, and 45 percent believe the act of asking a father for his daughter's hand in marriage is a "necessary courtesy" (just three percent found it "sexist and offensive"). And it turns out, a majority of the married people surveyed are hopeless romantics -- 58 percent believe in love at first sight.

Marriage Research