Well I don't see or mean for this piece to picture Summer and Ozpin to be romantically involved. Its more like on Ozpin and Summer's side its a King and a Pawn whereas on Ruby and Oscars side it's a King and a Queen. So Ruby and Oscar represent hope and working together equally(the new generation) whereas Summer and Ozpin represent the tragedy and inbalance/failures. My friend and I have this headcanon where Ozpin "uses" Summer as a pawn. So this piece is showing that Oscar is not like Ozpin and he will do things the right way without leading people to their deaths and Ruby wont end up like Summer hence they are in the light and not the dark.