Evangelical Christians are very much against same sex marriage last time I checked. They are also against sex outside marriage. The only difference is that Protestants generally allow birth control. But even some followers of the fundamentalist sects (like the creepy Duggars) are against that.
I know. My point was, that Bible Alone approach is an unpredictable random process: some Protestant sects get some aspects of sexual morality right and others wrong, and some Protestant sects get some aspects of liturgy right and others wrong. That is because they lack theological tools to understand sexuality and liturgy.