A "Radio song girl" isn't a real girl. It most likely fits with their redunant theme of moving to LA to become famous, then getting homesick and realizing it wasn't as great as they had imagined.
Ryan sings it as if he's being "tempted" to reach through the radio, and get to LA as if it's a kingdom and Radio Song Girl is the princess of that kingdom.
I forgot to add:
A "Radio song girl" isn't a real girl. It most likely fits with their redunant theme of moving to LA to become famous, then getting homesick and realizing it wasn't as great as they had imagined.
Ryan sings it as if he's being "tempted" to reach through the radio, and get to LA as if it's a kingdom and Radio Song Girl is the princess of that kingdom.