Recently, the American Supreme court has allowed homosexual marriages. Adultery or inapropriate sexual misconduct is one of the Noahide laws. If homosexuality is spoken against in the Torah, how does it affect the Noahide people as marriage is supposed to be a living and Godly bond between a man and woman (or is this prohibition just for Jews, and not gentiles)?
As you inferred, homosexuality is a severe transgression of 1 of the 7 universally accepted Noachide laws obligating all people. Accordingly, whether they think they are “married” or not, anyone who transgresses this sin, according to traditional sources does not go to Heaven. What these people mistakenly think as “marriage” has absolutely no validity or ramications, just in the fact that people who live together sin on a regular basis, and every single time they do so, they will be punished in the World-To-Come for a very serious offence. What is (!) historically significant here is that the Midrash (Breishit Rabba 26, 5) teaches that the Flood erased Noah’s generation because they recognized same-sex marriages. Similarly, the Talmud (Hullin 92b) teaches that the gentiles are commended for the fact that even though there were always individual deviant homosexuals, their governments don’t officially accept or recognize same-sex “marriages”. Democracy is great until it anarchically does away with basic guidelines. When America crossed this “red-line”, they have deviated from a very significant norm and will undoubtedly regret it, and hopefully will correct themselves. It can’t be a coincidence that this is also the first anti-Israel government in American history, for unfortunately, their ideology calls for a break not only from the Bible but from basic traditional norms, values and allies.