Several European countries have taken the step of allowing same-sex couples to formalize their relationship, through the institution of registered partnership or through a gender-neutral marriage institution. The Nordic countries are in the lead. In this way, the legal systems want to distance themselves from unequal treatment based on sexual orientation. The process has been fueled by a dynamic interpretation of the European Convention on Human Rights (ECHR) and the EU Charter of Fundamental Rights. At the same time, this development has been strongly challenged by religions, as reflected in the opposition of Poland, Lithuania and Latvia, among others, to the equation of same-sex relationships with heterosexual ones in EU cooperation. The lack of a uniform European approach leads to legally "limping" family relationships; a legal relationship is recognized in one country but not in another. This PhD project takes as its starting point the legal and faith-based approach to same-sex relationships. It analyzes the ideas of free movement of citizens and equal rights in the light of the right of each Member State to maintain its national specificity, whereby faith is important. The analysis takes into account, on the one hand, the new EU international family law regulations, primary EU law and the ECHR, and on the other hand, the legal situation primarily in Lithuania, Latvia and Poland. The central research question is to investigate the potential of the Europeanization process to bring the European legal systems closer together.