There is code that mandates uniformity across states for certain aspects of divorce. One is that if there are minors then the person filing has to be a resident of that state for at least six months. That six month requirement is so a person can't move away and immediately file there forcing the spouse who stayed to go to that other state for the divorce and custody process.
Since your youngest is now an adult that doesn't apply. The framework would have to be what his new state has as the rules for filing divorce. Better to find out sooner than later what the gotchas are. A lawyer ought to be able to advise you whether your state or his state would be more favorable in a divorce. Is either state a community property state? If the marriage has assets (money, house, etc) you may want a divorce in that state, I think. Get consultations with multiple lawyers (1) to ensure you get a consistent response and (2) you get a sense of which lawyer has better and more practical time-tested strategies.
While only eight states observe community property laws, there's still a good chance this affects you. That's because 25% of the American population lives in one of these
community property states. So perk up your ears if you're a resident of Arizona, California, Idaho, Nevada, New Mexico, Texas, Louisiana, Wisconsin or Washington.
Community property touches everything from personal property ownership to debt to divorce and inheritance... .