Your boyfriend is the client of the criminal defense attorney, even if you'd been paying the bill. The problem is, anything the lawyer discusses with you will no longer be protected by lawyer-client confidentiality, despite you having a POA, because you are not the client; therefore, discussing anything about the case with you could theoretically expose information to the prosecution (e.g. if they were to subpoena you and put you on the witness stand). The lawyer would need your boyfriend to specifically, in writing, acknolwedge the risk and apoprove the lawyer speaking to you in order to ethically discuss matters with you and share information.