Background Prior studies suggest that poor physical health, accompanied by functional disability, is associated with increased divorce risk. However, this association may depend on gender, the socioeconomic resources of the couple, as well as the social policy and social (in)equality context in which the illness is experienced. This study focuses on neurological conditions, which often have substantial functional consequences.

Methods We used longitudinal population-wide register data from the years 2007–2016 (Denmark, Sweden) or 2008–2017 (Finland, Norway) to follow 2 809 209 married couples aged 30–64 for neurological conditions, identified using information on specialised healthcare for diseases of the nervous system and subsequent divorce. Cox regression models were estimated in each country, and meta-analysis used to calculate across-country estimates.

Results During the 10-year follow-up period, 22.2% of couples experienced neurological conditions and 12.0% of marriages ended in divorce. In all countries, divorce risk was elevated among couples where at least one spouse had a neurological condition, and especially so if both spouses were ill. The divorce risk was either larger or similar for husband’s illness, compared with wife’s illness, in all educational categories. For the countries pooled, the weighted average HR was 1.21 (95% CI 1.20 to 1.23) for wives’ illness, 1.27 (95% CI 1.25 to 1.29) for husbands’ illness and 1.38 (95% CI 1.34 to 1.42) for couples where both spouses were ill.

Conclusions Despite some variation by educational resources and country context, the results suggest that the social consequences of illness are noticeable even in Nordic welfare states, with the husband’s illness being at least as important as the wife’s.