A UK Civil Partnership is the same as a California Domestic Partnership. If this person doesn't have a proper visa would it be a problem? One element have been residing in California for over 3 years.
No children, no property and nothing to be divided we have been separated for over 5 years.
Depends. The issues that arise are whether there is minor child, where the child resides, is there property (real or personal) in California and many for factors. As a California attorney I can't speak to whether a UK Civil Partnership is the same as a California Domestic Partnership. But depending on the facts there may be several options.