Carolyn Compton and partner Page Price were ordered to split up by District Judge John Roche Jr. due to a morality clause in Compton's 2011 divorce decree, The Dallas Morning News reported Wednesday.
The clause, common in Texas divorce cases, prevents an unmarried parent from having a romantic partner stay in the home overnight if children are present.
Compton has two daughters from her marriage.
A man and a woman in a serious relationship can get out from under the legal provision by marrying but same-sex marriages aren't recognized in Texas.
The lawyer representing Compton's former husband said he wanted the morality clause enforced for the benefit of the children.
"The fact that they can't get married in Texas is a legislative issue," said Paul Key. "It's not really our issue."
Compton and Price haven't ruled out an appeal.