i think khiac72 is right, this song is about sleeping with a girl who is underage. she's probably 17, since he says she'll be legal soon. he sees their relationship as just sex, but she is in love with him and sometimes he feels bad about that ("in the middle of the night i have a breakdown of sorts, with regret creeping in"). he doesn't want to end things with her because he's afraid she'll report him to the cops out of spite.
i think khiac72 is right, this song is about sleeping with a girl who is underage. she's probably 17, since he says she'll be legal soon. he sees their relationship as just sex, but she is in love with him and sometimes he feels bad about that ("in the middle of the night i have a breakdown of sorts, with regret creeping in"). he doesn't want to end things with her because he's afraid she'll report him to the cops out of spite.