There are two major proposed forms of dark energy: the cosmological constant and the quintessence scalar field. However, the former has the cosmological constant problem and the latter does not have observational evidence to support the theory. In this paper, we propose a dark energy paradigm to solve the cosmological constant problem and to predict lepton masses as evidence. The dark energy paradigm is a unified dark sector that is based on Planck's dimensional analysis, Lambda CDM, energy conservation, and force equilibrium. We find that dark energy can vary from the cosmological constant to the Planck scale. We find that the predicted values of lepton masses based on the dark energy paradigm agree with the observed values to 1% (or within error ranges).