You’ve mostly got it, I think. Adultery is a sin, but it’s a sin in the past. As long as you resolve to never do it again, you’re fine. Homosexuality is considered a sin, but it’s ongoing, so you commit it again anew every time you have sex with someone of the same gender as yourself (or possibly if you lust after him, but what qualifies as “lust” is up for debate). There’s also repentance, where you promise to never do it again and actually try to keep your word, where homosexuals generally do not promise this.
Divorce is where you are going astray. Divorce is also a one-time sin for the divorcer. Re-mariage is a one-time sin. You are not required to give up your husband or wife when you convert back to Christianity. (Remember, every time you willingly sin, you are converting away from Christianity.)
As for Kim Davis, she married a husband who she divorced over adultery, which makes it where he’s the one who is guilty, not her. Then she married husband 2, divorced him, married husband 3, divorced him, and then married back to husband 2. So the last marriage isn’t sinful, and the last divorce is of questionable sin status.
She also had a conversion to a more strict form of Christianity since then, and thus is not required to divorce her current husband, and in fact would be a sin for her to do so outside of certain circumstances. Any other divorces or remarriages are in the past and no longer count.
Sure, God hates divorce. He also thinks lying is an abomination. They all can be forgiven.
Now, under less theological terms, it’s because Christians have faced divorce or had friends who did, which made them go back and question their old rules and look for ways out. Christianity is all about this balance between judgement and mercy.
The same thing is happening with homosexuality, but it’s taking longer due to lack of out friends and never having to worry about facing it themselves, making it hard to empathize. But, every day, more and more Christians are coming in contact with homosexual people and struggling with finding a balance. Most stick with “It’s sinful, but who am I to judge,” but that’s really shaky.
This is why I continue to argue that the best course of action is to still stick with sola scriptura and even biblical literalism, and argue that we don’t know exactly what the Greek words that reference homosexuality mean, and that, without reaffirmation in the New Testament, the Old Testament rules are not necessarily valid.
People are looking for a way to accept homosexuality, so, I say, give them an out. Heck, it even helps me be more comfortable with it.