Remember how hard it was to forget Sarah Marshall even though she cheated? Anyway, it turns out, infidelity is not the prime suspect of marriages ending today, according to a new research by Co-operative Legal Services, a U.K.-based company.

The research looked at over 5 million U.K. divorce cases from 1970s till now and found that people today are half as likely to list cheating as the reason for their marriage ending with only 29 percent of divorces caused by infidelity. 

Modern couples are more likely to cite unreasonable behavior, with 47 percent of divorces quoting just that.

According to The Guardian, some examples of unreasonable behavior include "an unsociable husband making his wife feel guilty when she wanted to go out with her friends, a cross-dressing husband who decided to have a sex change, and a spouse withdrawing all the family savings."

What do you think? Is that worse than cheating? Admittedly, one of the biggest challenges to a relationship is how well a couple agrees and handles their money, together.