It's fair for states to set residency requirements for some things, such as whether you qualify for in-state tuition, or for hunting and fishing licenses. But

It's fair for states to set residency requirements for some things, such as whether you qualify for in-state tuition, or for hunting and fishing licenses. But I don't think that change of legal domicile should be anything but an overt act of volition. If you surrender your driver's license from your old state, and take a replacement from your new state, you have implicitly changed your domicile to the new state. But changing that driver's license may just be a concession to the fact that the new state is where you do most of your driving, and your old state might make it too inconvenient to renew licenses when you are physically elsewhere. Inconvenience alone does not make one's home change. You might physically spend 11.5 months out of every year in State X, but you might also have 2 parents, 1 grandparent, 3 siblings, 2 aunts and uncles, 5 first cousins, 15 old friends, and 30 cemetery burial plots for people whom you knew, and years of memories in State Y. I think your domicile is probably State Y, no matter what State X tries to claim. I have been where I am now for about ten years, but I still don't consider it "home". I'm only here because this is where the job is. I don't know when, exactly, I can ever return "home", or where it might be when I do, but the only places I have lived so far that really felt like "home" so far were Indianapolis and Madison, Wisconsin. Everywhere else has felt like the place belongs to someone else, and I was only allowed to temporarily stay there by some special indulgence. Any state that tries to tell me that it is my home, whether I want it to be or not, is probably not one that I'd want to be my home.