Magnetization instabilities in an insulating ferromagnet can be induced because of the spin Hall effect in a metallic side layer. In this paper we present a nonequilibrium thermodynamic approach to jointly describe magnetization dynamics and magnetic moment transport in the insulating ferromagnet. We employ nonequilibrium thermodynamics to derive the magnetic moment current which is injected into the ferromagnet from metal. We find that the magnetic moment current induces a thermodynamic effective field which depends on the penetration depth of the current. By considering vector magnetization dynamic equation we show that this term is able to compensate the damping and can possibly give rise to instabilities and the onset of self-oscillations. We apply to the case of thin YIG and we derive the corresponding instability. The model predicts the threshold for the onset of self oscillations, without tunable parameters, which are in good agreement with recent experiments.