Marriage is one of a very few things in life humans undertake where they are asked to commit to do something “for life” that they have never done before. And their closest vantage point is likely their parents’ marriage.
I think it’s not so much people take it lightly, as that they have no idea of what they are getting into and what kind of work a modern marriage involves.
It is amazing to me that people can consider entering into a lifelong contract with a partner and not have discussed 5, 10, 20 year goals. Seems like a common sense due diligence thing to do.
More than that - when my now fiancee proposed to me I was completely surprised by it, and literally couldn't process the question for a good couple of minutes. Thankfully she decided to leave me to it for that time and by the time she got back I accepted, but it occurred to me that a proposal is itself the only time you're asked to make a life-changing decision by surprise, and answer it there and then without being able to spend any time considering what the correct decision is.
I think it’s not so much people take it lightly, as that they have no idea of what they are getting into and what kind of work a modern marriage involves.