Are romantic partners more emotionally similar in the moment than simulated strangers: experiential versus couple effects

Emotional similarity in romantic couples has mostly been studied by examining whether emotional valence of both partners covaries over time, yielding one similarity score per couple. However, emotional experience is multidimensional and emotional similarity will change over time and situations. Moreover, strangers that show little initial similarity might become more similar when experiencing similar situations (experiential effect), raising the question whether being in a relationship actually adds similarity (couple effect) on top of these experiential factors. Here we investigate the contribution of experiential versus couple effects in partner’s emotional similarity, while embracing the multidimensional nature of emotional experience by assessing momentary emotional profile similarity scores. In two independent datasets, we compared romantic partners to simulated strangers and detected which experiential factors predict momentary similarity scores using regression trees. Results reveal that romantic partners are indeed more emotionally similar than simulated strangers, even when accounting for the identified experiential factors, amongst others, valence and contact with partner.