Objective Couples with fertility problems may experience marital or sexual distress which could potentially result in dissolved relationships. We investigated the likelihood of ending a relationship among women who did not have a child after a fertility evaluation. Design Longitudinal cohort study. Setting Danish women ever referred for primary or secondary fertility problems to a public Danish hospital or private fertility clinic between 1990 and 2006. Population A total of 47 515 women. Methods The data were linked to Danish administrative population-based registries containing demographic and socioeconomic information. Discrete-time survival models were used with person-period data. Each woman was followed from the year of her initial fertility evaluation through to 2007. Main outcome measures Effects of parity after a fertility evaluation on the likelihood of ending a marital or cohabitation relationship. Results After up to 12 years of follow up, nearly 27% of the women were no longer living with the person with whom they had lived at the time of the fertility evaluation. Women who did not have a child after the evaluation had significantly higher odds ratios for ending a relationship up to 12 years after the evaluation (with odds ratios up to 3.13, 95% CI 2.88-3.41) than women who had a child, regardless of their parity before the evaluation. Conclusions Parity after a fertility evaluation may be an important component in the longitudinal relationships of couples with fertility problems. Studies with detailed information on marital quality and relational well-being of couples with fertility problems are needed.