LGBT: Let Them Marry

Why is it that people who have roots in a polygamist/pedophilia religion say that these people can't have healthy, long-term relationships? Why is it that people who claim to study the Bible lie about how marriage is portrayed in it? What are they afraid of? People loving each other? People being able to have a say in how their long-term partner is cared for at the end of life? People getting inheritances?