Actually it is. Marriage was between a man and woman in Judaic practices which transferred over to Christianity and then to Islam. It was also practiced in many tribes and ethnic groups as a social contract and/or before their gods.
The government intruded only recently (recently in relation of how long humans have existed as communities) to make marriage a legal practice.
This is what the first amendment says. It basically says that the government cannot intrude and inhibit/prohibit the practice of religion. No where does it say that religion can’t have any influence on the government. It says that government cannot dictate what religion can do.
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
In addition, NO WHERE in the Constitution does it say anything about “separation of Church and state.” In fact, the word “Church” is absolutely no where in the Constitution.
So yea. If anything, the government is breaking the First Amendment by making the religious practice of marriage something that needs to be accompanied by a legal contract or else under the law you aren’t married.
Also the American Dream refers to the opportunity to be successful and prosperous and being able to have social mobility to move upwards because of hard work. Nothing to do about marriage. The American dream is being able to move up the economic ladder and being able to afford and be able to own your own home and your own car and buy whatever goods you want that you can afford. A lot of it is economic and financial. All of these things are why immigrants desire to come here. Because at home they are poor but they see that in America they can work their way out of poverty. It has nothing to do with the separation of Church and state.
So yep. Hope you enjoyed this civics lesson.