People also change and / or realize what they thought they'd like turns out to not be what they like. You can't know you will like a situation until you are living it.

I think entering a new job is similar, I may think I'm going to really like the job, but then when I'm actually doing the job I realize there are things I didn't consider and don't like it. Luckily, I can quit a job easily. In a marriage - you have to grow together if you want it to work.

There is a book which describes exactly what the author of the article realized too late, it's better to learn it via reading than in hindsight:

Difficult Conversations: How to Discuss What Matters Most