Online-dating, or the practice of searching for a partner on the Internet, is becoming more widespread and legitimate these days. According to some researchers, the search process is quite rationalized. This is underpinned by the fact that such platforms presuppose standard profiles, filters usage, and strike for a “better offer” just like on a market, stimulating users to reflect upon their performance. At the same time, there are religious online-dating platforms as well with their specific partner search normativity (i.e., Orthodox). Thus, there is a contradiction between the market practical rationality evoked by online-dating platform logics and substantial Orthodox Christian rationality, with the latter considering only marital relations as good, sacred and also, notably, those God has agency in. Relying on M. Weber’s conception of rationality, a grounded theory approach and an empirical base of 14 interviews, the paper reconstructs partner search rationality in the online-dating platform users’ categories (here, in the case of a popular Orthodox platform). Practical rationality is reconstructed in the “active search”, “time”, “convenience”, and “simplification” categories. For substantial rationality, which may contradict the practical one, such categories are “soulmate” and “consumer attitude”. The overcoming of the contradiction between the two rationalities is described in the categories of “self-control” and “the fight against temptation”. In regard to the relationship between an individual’s agency and God’s agency on the platform, although the informants believe active actions are required, the search for a marriage partner inevitably ends at “the God’s will point” — the result of what God wants.