In the classical view of General Relativity, time moves slower near massive objects where the gravitational field (spacetime curvature) is stronger. In the quantum view however, the gravitational force is produced by the quantum field represented by gravitons as its gauge bosons.
It appears, the more virtual gravitons are there (stronger quantum field), the slower time moves, but why? The concept of the gravitational attraction can be explained by the math of the exchange of gravitons, but how can the gravitational time dilation be explained at the quantum level?
I understand that we don't yet have a full theory of quantum gravity to explain what happens at the Plank scale in singularities. However, my question is far from such extremes and should have a logical answer without the full theory of quantum gravity.