In the paper, an effect of a second order phase transition has been considered in the context of the phenomenological model for a 2D charged system (2DCS) frustrated by the Coulomb interaction. The relationship between the order parameter and the charge was treated as a local temperature in the 2DCS. The existence of phase-separated states was shown to be a possibility in such a system. Various types of those states (strips, rings, etc.) were found by numerical calculations, and their parameters were determined. As the temperature is lowered, the 2DCS passes several phase transitions successively. Using the La(1–x)Sr(x)MnO3 manganite as an example it was shown that such a phenomenological model could be used to describe the phase separation close to a magnetic phase transition from a ferromagnetic state to a paramagnetic one when 0.10 < x < 0.15 and at the temperatures of 100 < T < 200 K.