The widespread use of social media has a transformative effect on people's work and lives. With the increasing information explosion and more cases of social media addiction, users have been always worried that they have missed some information. FoMO (fear of missing out) of mobile users emerges. FoMO is an important theory that explicates the underlying cognitive, psychological, and social processes of dark or negative sides of online information behaviour (Shen, et al., 2021). This paper

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... res the impact of FoMO of post-90s generation mobile users on romantic relationship in the context of social media. The questionnaire survey was conducted in December 2017. The sample size was 274 Chinese post-90s (people born in the 1990's) mobile social media users who were in love for at least one year and unmarried.. The statistical methods such as regression analysis were adopted. The impacts of FoMO on romantic relationship were analyzed from the perspectives of three dimensions of FoMO: cognitive, emotional and behavioural manifestations. The quantitative analysis of survey data employed the statistical package SPSS 26.0. The behavioural manifestation of FoMO has a significant negative effect on romantic relationships, while emotional and cognitive manifestations of FoMO have no significant effects on romantic relationships. This indicates that driven by FoMO, the post-90s mobile users often check the information in device frequently and subconsciously, resulting in excessive information behaviours, which does harm to the development of romantic relationship. It also implies that the view of simply treating the anxiety disorder FoMO as a psychological symptom is debatable.Conclusion. FoMO has affected users' interpersonal relationship and behaviour in the offline environment, especially for post-90s generation users. This paper enriches the research on the effects of psychology and information behaviour of mobile social media users on their interpersonal relationship.