Dense neutrino plasmas can develop instabilities that drive collisionless flavor exchange, equivalent to the emission of flavomons, the quanta of flavor waves. We treat these waves as independent linear degrees of freedom and develop a quasi-linear theory (QLT), including backreaction on the neutrino distribution and nonresonant neutrino–flavomon interactions, while neglecting wave–wave processes. In a statistically homogeneous, axisymmetric model, the saturated neutrino and flavomon distributions agree closely with periodic-box solutions of the original quantum kinetic equation. Our results provide the first theoretical interpretation for the numerical observations. They also show that flavomon phases have little influence on the final state, supporting QLT as a framework for capturing flavor evolution without resolving nonlinear small-scale dynamics.