this is a song about an affair... and the shame that comes along with it...
basically the man and woman connect deeper than with their partners...
but since its an affair, they need to deny their relationship
the second verse is about their sex... plain and simple... eventhough their connection is there, since its an affair... there is pain emotionally... probably because one of them just wants it to stay that way, while the other wants the relationship to move forward either they be together legally or move on from each other