That is NEVER the only issue.
Throughout history (at least until a few years ago), regardless of any cultural or religious beliefs, marriage has ALWAYS had a common element and that is there is ONE MAN and one or more women. There has NEVER been a culture where a union with more than one man or no men is recognized as a marriage.
Anyone who is willing to sacrifice thousands of years of values to satisfy the selfishness of less than five percent of the population is willing to sacrifice anything.
I don’t say I will agree with them on that issue, I won’t. My point is that there ARE those who agree with much of the conservative agenda, but not all. I want their support on the issues we agree on. That doesn’t mean one has to cave on the ones where we differ.