Key phrase here. The Christian position on marriage isn't just a religious one, but one based on nature and right reason. In other words, just a good common sense conclusion based on observation and thinking, rather than emoting. Romans 1 and Wisdom 13 lay this out very clearly.
Sorry, there is no higher standard of truth and ethics than the word of God and it is cultural suicide to place fallen reason above it. I for one will stand on the word and will not be shamed, shouted or ridiculed off of that one certain revelation of God. The consequences of a sin are not the basis for it to be named a sin, it is sin because it transgress the law/word of God. The temporal consequences are a gracious reminder that the eternal consequences of sin are real and that fallen men need mercy that can only come through the sacrifice of Christ.
Proverbs 3:5 Trust in the LORD with all your heart, And lean not on your own understanding;