My husband was declined for my auto loan

Does anyone know why does it mean and why it happened? So we both applied for auto financing and already signed all documents and everything, we paid downpayment, we got a car and driving on it around month. And today we got a letter that Kia Bank checked husband history, his score is 699 and they say they cannot provide credit on the terms he requested (but we already have it…) Im just confusing, because Im a main financing signer, so he is just like for his credit history, co-borrower or I dont know how to call it right. Why they can cancel him?