Well-regulated emotions, both within people and between relationship partners, play a key role in facilitating health and well-being. The present study examined 39 heterosexual couples’ joint weight status (both partners are healthy-weight, both overweight, one healthy-weight and one overweight) as a predictor of two interpersonal emotional patterns during a discussion of their shared lifestyle choices. The first pattern, co-regulation, is one in which partners’ coupled emotions show a dampening pattern over time and ultimately return to homeostatic levels. The second, co-dysregulation, is one in which partners’ coupled emotions are amplified away from homeostatic balance. We demonstrate how a coupled linear oscillator (CLO) model (Butner, Amazeen, & Mulvey, 2005) can be used to distinguish co-regulation from co-dysregulation. As predicted, healthy-weight couples and mixed-weight couples in which the man was heavier than the woman displayed co-regulation, but overweight couples and mixed-weight couples in which the woman was heavier showed co-dysregulation. These results suggest that heterosexual couples in which the woman is overweight may face formidable co-regulatory challenges that could undermine both partners’ well-being. The results also demonstrate the importance of distinguishing between various interpersonal emotional dynamics for understanding connections between interpersonal emotions and health.