  The spread of new products in a networked population is often modeled as an
epidemic. However, in the case of `complex' contagion, these models {do not
capture nuanced, dynamic social reinforcement effects in adoption behavior}. In
this paper, we investigate a model of complex contagion which allows a
coevolutionary interplay between adoption, modeled as an SIS epidemic spreading
process, and social reinforcement effects, modeled as consensus opinion
dynamics. Asymptotic stability analysis of the all-adopt as well as the
none-adopt equilibria of the combined opinion-adoption model is provided
through the use of Lyapunov arguments. In doing so, sufficient conditions are
provided which determine the stability of the `flop' state, where no one adopts
the product and everyone's opinion of the product is least favorable, and the
`hit' state, where everyone adopts and their opinions are most favorable. These
conditions are shown to extend to the bounded confidence opinion dynamic under
a stronger assumption on the model parameters. To conclude, numerical
simulations demonstrate behavior of the model which reflect findings from the
sociology literature on adoption behavior.
