We combined Bakker and Demerouti's spillover–crossover model with Taylor's biobehavioral perspective, tested the comprehensive model, and pursued a set of gender‐related research questions. Negative work interactions were expected to entail two strain responses, high‐ and low‐arousal negative affect. Both should be related to cortisol secretion but transmitted via different social pathways, a positive and a negative one. During a 7‐day ambulatory assessment with 56 couples, we assessed daily variations in the severity of negative social interactions at work and at home along with participants' affect and cortisol levels. Using multilevel structural equation modeling, we found evidence for the three hypothesized processes: strain at work as a consequence of social stress, spillover of strain into the home, and crossover to the partner. On socially more stressful days, participants showed increased high‐ and low‐arousal negative affect at work. Low‐arousal negative affect spilled over into the home. Only for men, high‐arousal negative affect spilled over, and only women showed a tendency for slowed decline of cortisol levels on more socially stressful days (i.e., slower recovery). Surprisingly, high‐arousal negative affect at work tended to be negatively related to partners' high‐arousal negative affect. Commonalities predominated differences between men and women. Copyright © 2016 John Wiley & Sons, Ltd.