This girl wants to keep up the sexual connection they have after they have ended their "relationship", even though one or both of them realize they don't belong together. He knows it is only time before she moves on too, and doesn't want to remain vulnerable as her lover if he knows they no longer have a relationship. "I'll be pouring tears into your drying eyes"
John doesn't believe people should stay friends after being lovers, because after the feelings have been there, we'll want to keep them alive by thinking of the good times, but he wants to move on.
"Think we'll never fall into
The jealous game
The streets will flood
With blood of those who felt the same"
Perhaps he knows he will become jealous if his future GF still is friends with her former lovers, so that's why he's saying you can only be ONE and he is wanting to live the same as he wants from others. Friends. Lovers. Nothing. "We can really only EVER be one" "So give it up" means he wants her to stop coming back to him, because he understands he is still vulnerable himself and is tempted to hold on to a dying relationship in an empty way.
I think this song has a couple meanings to it.
Perhaps he knows he will become jealous if his future GF still is friends with her former lovers, so that's why he's saying you can only be ONE and he is wanting to live the same as he wants from others. Friends. Lovers. Nothing. "We can really only EVER be one" "So give it up" means he wants her to stop coming back to him, because he understands he is still vulnerable himself and is tempted to hold on to a dying relationship in an empty way.