PhD first-year transfer including credits
I can add to this a bit more about credits if needed (as per my comment), but for your advisor, I'd just open with the fact that you need to change programs for non academic reasons and that you would be happy to discuss it with them. If they need more information then they will follow up. Otherwise there isn't really a need.
But it would be good to leave on good terms with them. As a first year student you probably don't have a deep relationship yet, so it may not matter, but anyone and everyone who has a good opinion of you can be an asset going forward in your career.