This simple animation illustrates how curved space-time deflects path of light. In the vicinity of massive bodies the space-time gets locally more curved, so that photons are forced to travel along longer paths there. The another question is, why space-time behaves so in presence of massive bodies. The answer may come from presence of two space-time arrows again: the first (classical) one is defined by transverse waves of light which are giving expanding perspective (red shift) at long scales, the second one by longitudinal ("scalar") waves of vacuum which are giving contracting perspective at short scales (blue shift) for us. As one can guess, once transverse and longitudinal waves come in ballance, then the space-time looks flat and steady-state (local expansion by photons is balanced by contraction of space induced by scalar waves). Once one of kind of ripples prevails, then the space-time gets curved locally and it exhibits "lensing" at large scales.
In dense aether model the massive bodies are source of this disbalance itself due to their ability to shield transverse and longitudinal components of omnipresent vacuum energy at different distance. Analogously to water surface the transverse waves of vacuum bear high energy density, but they're relatively slow. The extradimensional scalar waves are much weaker, but they propagate much faster than the speed of light in similar way like sound waves at the water surface. Every massive body thus shields virtual photons at relatively short distance (Casimir field) but longitudinal waves (virtual neutrinos) at much larger distance (gravitational field). The Casimir field is thus curved in similar way, like the gravitational field and it exhibits attractive force - but it contains excess of scalar waves and it contracts time arrow. Whereas gravitational field contains excess of virtual photons and it dilates the time arrow instead.