The purpose of this article is to analyze the optimal legal structure which allows two persons of the same sex to create a permanent union of intimate and exclusive nature for the purpose of living a common life in Taiwan law. This article is divided into three parts. Firstly, it explores the meaning of freedom of marriage under Taiwan Judicial Yuan Interpretation No.748 [Same-Sex Marriage Case]. Secondly, it argues that we should set up same-sex union relatives as a legal structure for two persons of the same sex in a permanent union of living a common life. Finally, it concludes by proposing draft legislation relative to Taiwanese same-sex union relatives.