Such relationships exist. But in no way are such anywhere as common as those relationships in which men earn more than women. And that disparity is primarily because, as IdiocyInAction said, women don't want to be in relationships with men who earn less, not because men don't want to be in relationships with women who earn more.
"because men don't want to be in relationships with women who earn more."
This on it's own may be a correct statement however as you phrase it makes it sound like this this is the defining reason.
It's not, there are anecdotes of (insecure) men not wanting this dynamic, but a majority of cases the opposite is true. Women seek men of higher value (earning potential), not less. Men seek youth/beauty.
