You're doing exactly what her boyfriend is talking about. Romanticizing it.

Also, I didn't say anything about what she wants. I simply said that a common law marriage negates every justification you had for getting married. In the eyes of the law marriage is purely ceremonial.

Fun fact, common law negates almost everything you said. Marriage is indeed just a formality in this day and age.

OP my advice to you is to ignore everything that was said in your post on r/relationshipadvice. Stop worrying about the future and enjoy what you have now. Marriage is indeed an outdated formality that doesn't define a good relationship.