  We have performed first order reversal curve measurements of the
temperature-driven metal-insulator transition in VO$_2$ thin films, which
enable quantitative analysis of the hysteresis behavior. An unexpected
tail-like feature in the contour plot of the reversal curve distribution
indicates the existence of metallic domains, even at temperatures below the
closing of the hysteresis. These domains interact with the surrounding medium
and change the reversal path relative to a path from a \emph{fully} insulating
state. With this in mind, and assuming that such interaction persist through
the entire phase transition, we develop a model where the driving force (or
energy barrier) in charge of opening a hysteresis in VO$_2$ are inter-domain
interactions. This model is intrinsically different from the Preisach model
usually used to describe hysteresis; given that it looks for the microscopic
origin of the hysteresis, and provides physical parameters to characterize it.
