I don't see what two gay men or two lesbian women doing in the privacy of their own home has anything to do with gay marriage.

At face value, no one is affected. Thati s how it is presented, and that is what the majority of people believe. Even the people who fight for gay marriage believe that. But the people who are really in the know know what it's really about. And that is the redefinition of marriage.

Science, that thing you love, consistently shows that gay over 50% of gay couples have non-monogamous agreements, i.e. open relationships. This is apparently well known within the LGBT community themselves, but not something they want known to the wide public (just yet). This article, "Were Christians Right ABout Gay Marriage All Along?" mentions the scientific studies done for proof and argues that we should allow gay marriage to be a slippery slope for more honest non-monogamous marriages. (Or something not called marriage at all.) But this is exactly the destruction of marriage after all. The article is here: www.thedailybeast.com/articles/2014/05/27/did-christians-get-gay-marriage-right.html

Now why it's morally acceptable to the public to argue for the destruction of marriage I don't know. The situation gets worse the further back you look. The LGBT movement is of course well-linked with the feminist movement, whose most ardent members thought it was necessary for the liberation of women that marriage be destroyed. Non-monogamy and homosexuality is the way to do that, so the advocated openly for promiscuity and divorce.

They have largely been successful, completely dominating society's morality so far, so I see no reason why it would magically stop now just so a few of the actual good gay people won't have their reputations sullied.

I think my argument is undeniable so far, but I will add that the movement has had no regard for religious freedom so far in Europe, the Church of England being sued by a gay couple already. A quick look at the history and legal precedent of our government interfering in religious marriages isn't pretty. The government said they could force Mormons to stop practicing polygamy, even taking their property until they stopped. So if it gets to the point where everyone's accepted homosexual marriage except for the big churches, they could be sued by, say, a loving gay couple who is cellibate and just wants the right to consummate their relationship like everyone else. Then the court would have to decide if the church has the right to discriminate if their religion tells them to. The trend and precedent, again, gives the government the ability to infringe on religious practice. So, yes, in 20 years or so, I could see this happening.

So aside from the whole history and what's actually going to happen for people who know about it, then yes, it doesn't affect anyone. If you don't count the entire society as anyone.