On the one hand, Japan realizes relations between the two countries should not proceed in their current state; on the other, some Japanese choose not to give up their incorrect view of history.
China-EU relations are less complicated. When the EU negotiates with China on economic issues, it isn't clouded by the Taiwan question or security fears.
China isn't interested in making relations any more complicated than they already are. China isn't trying to challenge America's No. 1 status in the world.