Those issues are usually spelled out in the final separation agreement (by whatever name depending on the state). My former brother-in-law figured it was worth getting out of his first marriage without a major suit if he agreed to pay his (then only) son’s education costs, regardless of how long the kid chose to stay in school. IIRC, the kid only went for a Master.
It’s hard to imagine college education for 3 kids wasn’t factored in when your friend and his ex were going thru the divorce. Both had to have lousy lawyers. Or maybe none?
The wife’s family were all lawyers (father; brother). The husband didn’t want the divorce and chose to ignore most of the proceedings. He felt that because she packed up and moved out, and the kids weren’t speaking to him, it was her fault. He felt that he was righteous and she was not and the courts would see that.
Big mistake. After it was all over and all the property was split, the courts came back at him for college tuition. The argument (which the courts upheld) was that both of the parents were college educated and it was the parents’ obligation (mostly him) to see that the kids received at least as much education as their parents. The implication was that if the parents had been HS drop outs, he would have only been responsible until they were 18.