Same-sex relationships are not the same as a heterosexual marriage.
I don't think there has ever been a person who is not sexually broken in some way.
That brokenness may be a genetic deformity (born that way), the result of twisted modeling from within the family or outside, abuse/molestation, improper initial sexual experiences or choice (sex outside of marriage in any form).
However, nature, culture, history and religion all point very consistently to a norm. If not, this debate would have been over long ago.
Casting stones does no one any good, nor does trying to make the abnormal normal.
I would suggest our greatest challenge is not each other, but honestly facing and dealing with our own brokenness.
Scientist are not sure why two genders evolved, but it makes sense that one gender focused on protection and provision, while the other on reproduction and nurture.
It is interesting that the Bible indicates just that; Adam was created, and out of that single gender Eve was created. Both had unique purposes that brought 'completion' or 'oneness' when re-united in marriage.
It is not only the perfect setting for reproduction and the nurture of young. It is also a relationship where both genders find 'balance' in a number of ways through an exclusive, life-long commitment in marriage.
One obvious example is the physical expression of oneness in sexual union between a man and a woman. Male and female were made for each other sexually. Homosexual union does not naturally fit.
Same-sex relationships can certainly have genuine love and many other qualities. But it is impossible to match the diversity and balance of heterosexual marriage.
Same-sex relationships have every right to be defined in specific ways. They should also have the necessary protections and justice. However, to provide that within the scope of the marriage relationship is not right or logical.
I have no desire to make you defensive or offend you. I hope we can debate these issues in a polite and fair way. I know I have much more to learn, but this is what I have come to so far.
You are right that marriages in the western world have taken a downward turn in the last few decades. I have some thoughts about that for later.
In the historical context I was speaking of, marriages have been between a man and a woman across cultures, religions and human history.
You are right that homosexuality has always been around and is present in the animal kingdom. But in neither places to a great degree. Among animals there is often a extenuating circumstance.
Among humans it has been and is more often rejected as 'abnormal' or worse. If you re-consider what I listed as possible causes of homosexuality, only one or maybe two would be a choice.
There is certainly a broad genetic variation between masculinity and femininity expressed in genders. However, there is a point where a unusual genetic variation becomes abnormal. I do not say that in a moral sense at all.
The influences of society and family, abuse or molestation also must have a factor in our sexuality. Those are also amoral factors on the part of the recipient.
Our initial sexual experience may be a choice, and therefore possibly unwise. Some people experiment sexually later in life as the Apostle Paul spoke about in Romans. Those are choices.
As I stated earlier, I think we are all sexually broken. God does not excuse us because of that. We are held accountable for how we handle our brokenness.
My experience has been to tightly hold on to two truths. First,'those who do such things will not inherit the Kingdom of God'. And second,'if we confess our sin He is faithful and just to forgive us'.
I have had years of daily mercy, and all to brief periods of victory. I try to keep the perspective that this present time is a micro-second in the span of eternity. This is where God has led me so far.
Sometimes our battle to convince others is nothing more than a battle to convince ourselves.
I suspect you have wrestled longer than Jacob. Sometimes our measure is how hard we fight, but sometimes it is who we surrender to.
I found a little known book by C.S. Lewis to be profound; 'Till We Have Faces'.
My best wishes to you!