I think this is waking up the next morning after a fight with your lover/spouse and feeling regret and wanting to make amends and start over today.
"Oceans of Diamonds always shine" (the night sky/sleeping on it) smooth out below (the problems/fights/bad feelings below/down on earth)
He's giving up defending his side of the fight and asking for the other to join him, and to show how it could have been/could be when they don't fight like that anymore.
I think this is waking up the next morning after a fight with your lover/spouse and feeling regret and wanting to make amends and start over today.
"Oceans of Diamonds always shine" (the night sky/sleeping on it) smooth out below (the problems/fights/bad feelings below/down on earth)
He's giving up defending his side of the fight and asking for the other to join him, and to show how it could have been/could be when they don't fight like that anymore.