A generalized Falicov-Kimball model is applied to study the phase diagram of metal ammonia solutions. The model includes a fluid-fluid interaction term and an electron-fluid interaction with a hard core and an attractive tail. Mean-field theories are derived for the localized and delocalized electron phases using ideas from the slave-boson approach to the Hubbard model. The attractive force stabilizes both the homogeneous delocalized electron phase and a regime where the electrons localize in cavities devoid of fluid particles. In its absence, the localized states are found to be unstable towards phase separation, in contrast to previous predictions. The Gaussian fluctuations and structure factors derived from this theory suggest the-existence of bicontinuous channels percolating through the system. These findings agree qualitatively with experiments and computer simulations.