The principal research question is whether the absence of a uniform legal framework governing the status of cohabitation reflects a deliberate and sufficiently justified legislative choice, rooted in the factual nature of such relationships and the special constitutional status of marriage, or whether it creates inconsistencies that require legislative intervention. The article advances the thesis that it is possible to clarify the legal concept of cohabitation and the criteria for identifying such relationships without equating their legal status with that of marriage. Greater terminological consistency could enhance legal certainty and contribute to the uniform application of the law, while remaining compatible with the special protection afforded to marriage under Article 18 of the Constitution of the Republic of Poland. The first part examines the difficulties of defining cohabitation as an informal relationship. It then compares cohabitation and marriage, with particular emphasis on their factual similarities and the fundamental differences in their legal status. The final part assesses the existing legal framework de lege lata and proposes de lege ferenda reforms to provide greater clarity and coherence to the legal status of cohabitation.