Offer your thoughts or opinion on the input financial query or topic using your financial background.

Live in California but work for Illinois-based company
They might be concerned with having to charge sales tax in California if they have a single employee in California, creating a nexus situation with CA. If that's the case, or even if there is some other issue, you might be able to switch from being a W2 employee to being a 1099 independent contractor. There's a host of additional issues this could cause, but it alleviate the nexus problem (if THAT is the problem). Here's a terrible solution you can bring up, but shouldn't do under any circumstances: offer to set up a mailing address in an allowed State, and give your company plausible deniability with regards to your legal residence. Obviously, this is a terrible idea, but exploring that option with your employer would help you suss out what the actual objection is. Ultimately, anything said here about the reason is just conjecture. You need to talk to the decision maker(s) about the real reason behind the denial. Then you can talk through solutions. Also - don't forget that you can get another job. If you are serious about a future with your girlfriend, you should put that relationship ahead of your current employment comfort and security. If you are willing to walk away from your position, you are in a much better situation to negotiate.