The question is why to get married?

Weird answer, no reason that science will offer and science has crowded out all other ways of finding truth. If someone or a nation wanted to promote healthy families, they have to foster both moral knowledge and moral instinct... that is why we have families. To do that, you would have to start teaching the basics of philosophy the way you teach children reading, in grammar school, like they always sued to. Teaching that would not just teach the critical thinking skills everyone agrees are missing these days, but also morality... which everyone seems to agree is missing so much that we are in a moral crisis. Science is great, but we need to teach more than that because it alone does not teach the most important lessons.