That's true in marriages, but it's not actually true in dating. You may have that perception but research on the topic says this isn't the case. And finding another relationship isn't the same as finding another good, healthy relationship that you actually want to be in.
The results came from an analysis of the aptly named “How Couples Meet and Stay Together” survey, collected from 2,262 adults with opposite sex partners who answered questions about their relationship status between 2009 and 2015. Women initiated 69% of divorces, compared to 31% of men. But if men and women were living together without marrying, each gender was equally likely to initiate a breakup.