Deposit for rental property

[Chad C.]

Hi BP Landlords and Investors, Got a quick question for you! I have a rental in Arizona. A couple (boyfriend and girlfriend) move in together and sign lease Jul 2015. They deposit $1150 in Jul 2015. Each year the contract has been extended. In Oct 2017 girlfriend moves out but doesn't inform but doesn’t inform landlord. But Boyfriend continued to make monthly rental payments. X-GF is asking for deposit back. But she never informed Landlord that she moved out. Does all of deposit go to the boyfriend that is paying monthly rent? Or does only half go to boyfriend? And other half x-girlfriend looses her share? Just wondering if anyone can help answer this question.