This paper tested why people differ with regard to whether they believe it is possible to find enduring love. Variations were assumed to be due to differences in people’s experiences. Those who experienced dysfunction in their family of origin and who did not have positive relationships role-modelled to them were expected to be less likely to have positive lay beliefs about romantic relationships. Positive lay beliefs, in turn, were hypothesised to impact on dysfunction in own romantic relationships later on in life, which were in turn expected to affect relationship satisfaction. In other words, positive lay beliefs were tested as one potential mechanism through which family dysfunction whilst growing up impacts on relationship dysfunction in later adult life. This paper presents a pilot study (N = 176) which introduces a measure for ‘positive lay beliefs about romantic relationships’, and finds this measure to be associated, as expected, with dysfunction in the family of origin. The main study (N = 435) then tested the full hypothesised model (family-of-origin dysfunction → positive lay beliefs → romantic relationship dysfunction → relationship satisfaction) with structural equation modelling, and found that the model fitted the data very well, confirming the hypotheses. It was concluded that lay beliefs about whether or not it is possible to find enduring love are an important mediator of the effects of family-of-origin dysfunction on later romantic relationship satisfaction.