I think when he says he's been to both hemispheres of the world, it's a metaphor for her body. So like this may sound a little weird, but like the top and bottom half of her body. The top would be like her mouth: they can talk, be in love, kiss, hold each other, etc. The bottom would just be sex. So he can't decide if he is with her for the lust or love. I hope that makes sense.
I think when he says he's been to both hemispheres of the world, it's a metaphor for her body. So like this may sound a little weird, but like the top and bottom half of her body. The top would be like her mouth: they can talk, be in love, kiss, hold each other, etc. The bottom would just be sex. So he can't decide if he is with her for the lust or love. I hope that makes sense.