We study decoupled numerical methods for multi-domain, multi- physics applications. An approximate intrinsic Robin condition is derived for the semi-discrete model of the coupled heat flow model problem. This new interface condition is justified both mathematically and physically in contrast to the classical Robin interface condition conventionally introduced for decoupling multi-modeling problems. Based on the intrinsic Robin condition, an equivalent semi-discrete model is introduced, which leads to a general framework for devising effective decoupled numerical methods.