The primary way to account for connectivity in polymer melts and solutions, beyond meanfield models such as the Flory-Huggins theory, is to use the Random Phase Approximation (RPA) that accounts for harmonic fluctuations in the free energy. Indeed, a large amount of work has used the RPA to study coacervate or polyelectrolyte complex phase behavior, with several modifications to account for excluded volume and non-Gaussian conformations. We can show that this cluster expansion approach is capable of reproducing the fundamental result, given by Kudlay and Olvera de la Cruz and later generalized by Qin and de Pablo. βf