Modeling of dynamic networks -- networks that evolve over time -- has manifold applications in many fields. In epidemiology in particular, there is a need for data-driven modeling of human sexual relationship networks for the purpose of modeling and simulation of the spread of sexually transmitted disease. Dynamic network data about such networks are extremely difficult to collect, however, and much more readily available are egocentrically sampled data of a network at a single time point, with some attendant information about the sexual history of respondents. Krivitsky and Handcock (2014) proposed a Separable Temporal ERGM (STERGM) framework, which facilitates separable modeling of the tie duration distributions and the structural dynamics of tie formation. In this work, we apply this modeling framework to this problem, by studying the long-run properties of STERGM processes, developing methods for fitting STERGMs to egocentrically sampled data, and extending the network size adjustment method of Krivitsky, Handcock, and Morris (2011) to dynamic models.