CTL: A married parent can decide not to pay a penny towards college even if that parent went to Harvard, earns a seven digit salary and the grandparents fully paid his college in his youth. No court world generally force such a married parent to pay anything towards his children’s college.
Now if that parent is getting divorced, his spouse can litigate into forcing him to be legally responsible for a portion of the costs even though absent the divorce he’d have had no such obligation. Even though right from the outset he states that he wishes to not pay a penny towards any of his adult children’s college. And he makes no voluntary agreement with his spouse agreeing otherwise.
That demonstrates a different standard for married parents and for divorced parents.