This paper introduces formal models for emotional reasoning, expressing emotional states and emotional causality, using action reasoning and transition systems. A general framework is defined, comprised of two main components: 1) a model for emotions based on the Appraisal theory of Emotion (AE), and 2) a model for emotional change based on Hedonic Emotion Regulation (HER). A particular transition system is modelled in which states correspond to human emotional states and transitions correspond to restrictive (safe) ways to influence emotions while reducing negative emotional side-effects. The introduced emotional reasoning can be applied to guide a software agent’s actions for dealing with emotions while estimating and planning future interactions with humans.