In 2019, Taiwan became the first in Asia to legalize same-sex marriage (SSM). This article considers the social movement strategies and relational dynamics of three activist groups in the year leading to the landmark SSM legislation, respectively representing the “yes,” “no,” and “alternative” agendas in the public debates and social mobilization around the issue of equal marriage rights. Through a critical study of the three cases, this article examines how various campaigners shaped local SSM discourses and mobilized people to support, oppose, and question marriage equality, focusing on their social mobilization strategies and inter-group relational dynamics under Taiwan's political and legal structures. In so doing, it proposes a hybrid theoretical model to understand complex social movement and countermovement relations and dynamics.