So I can steal anything from anyone, claim I paid for it, and get away with it? Wow, I can't imagine why everyone doesn't do that! 🙄
Seriously, he would need some kind of proof that he paid for it. And if he's got a criminal record for stealing, and the OP doesn't, the police pretty much automatically side against the person with a record.
OP, if you actually held the ipod in your hands, why not just walk away with it? Tell him to call the police--if he stole it, and you know he did, there's no way he will call the police. Call his bluff. And your boyfriend was there in case he just decided to beat you up.