My Boyfriend's Apple ID on my Phone-What it Mean

Hi, community!  I  just got an I-Phone for work a week or so ago.  In getting around to establishing some of the settings, I discovered this morning that my new boyfriend's apple ID was on my phone already.   I'm wondering what it means that it appeared here.  I'm just learning about Apple ID's.  I do remember him saying he might show me how to download I-tunes, so maybe he tried to do that.  I am hoping someone can clarify why it might be appearing, and the significance of it.  Thank you!