Background: Research on partner-related has been neglected in the past. According to the attribution theory of fascination, partner appreciation is an integral part for a successful relationship. So far, however, no available validated instruments exist or the assessment of partner-related fascination. Hence, the aim of the present study was the development and validation of a new instrument to assess partner-related fascination (FfP). Methods: The questionnaire was validated in an online study including 265 individuals (aged 18-63). The psychometric properties and the dimensional structure of the questionnaire were investigated using internal consistencies, as well as exploratory and confirmatory factor analyses. Results: The factorial validation resulted in 2 subscales. The internal consistency was unsatisfactory for the first factor (alpha=0.58) but acceptable for the second factor (alpha=0.86). The results tentatively indicate that only the second subscale of the FfP should be used. This 8-item subscale, however, shows good psychometric properties and can therefore be applied as an adequate research instrument for the assessment of long-term partner fascination.