We hope you enjoy your holiday in New York. Car insurance is mandatory in New York State and you may find it to be expensive if you do not have a U.S. license. Some insurance companies add a surcharge if you do not have a U.S. driver's license.
I would first suggest seeing if the girlfriend's insurance company will allow you to be put on her policy while you are in visiting. If not shop around, many auto insurance companies will allow you to start your insurance with an international license but require you to get a State driver's license within 30 days.
We can help you find an insurance company to fit your New York needs.