i don't know how well established this is, but my and my friend (being the immature geeks we are) decided this song is about oral. let me know if this is obvious or not.
down to the well
the well being a vagina
felt like a river inside her bones
reference to female orgasm
what matter does it make if there'll be favorite songs playing in my head when we go down to the well
doesn't enjoy oral, but aslong as he's in a world of his own, with favourite songs playing in his head, he's ok.