Lower educated individuals have less stable unions across many Western countries. This is in line with Goode’s (1962) thesis that lower educated individuals experience more economic strain and are therefore at higher risk of union dissolution. Nonetheless, micro-level evidence is weak. This may be due to a concept of strain that is too limited or due to a focus on only one partner in the union. In this study, we broadened the concept of strain to cover multiple life domains and captured its experience by both partners in a union. We used data from the longitudinal Household, Income and Labour Dynamics in Australia survey (N = 47,360 union-years; 8,092 unions). Event-history mediation analysis showed that lower educated individuals experienced more strains not only in the economic domain but also in other life domains. Moreover, lower educated individuals tended to have partners who experienced more strains as well. In total, the joint experience of life strains explained 47% of the education gradient in union dissolution. These results suggest that life strains are pivotal to the stratification of family life.