There are many legal, and cultural reasons that marriage which you can easily look up online.
Marriage has been a thing since the dawn of man. It’s only recently become the cool thing to completely disregard marriages and bash them “because they are part of the system holding you down or screwing you over”.
The legal and cultural purpose of marriage has evolved overtime and will continue to evolve over time.
It can be a commitment of two people in love, but unfortunately that is not the only case.
In my case, I got married to my wife because it created a deeper invisible bond between us. The societal and legal benefits were just a bonus.
There are many trappings depending on your culture, class, and laws that ebb and flow
At the core of it marriage is a ritual that binds people together on a deep level that cannot be quantified or qualified. This can be polyamorous marriages or monogamous marriages.
If you want strip it down to its energetic level, marriage is an intangible connection of energy between people.
Even if you get separated and hate each other that connection is always there at least while you are alive.
Unfortunately this is true for what was historically common of unwanted marriages as well.
No matter what the circumstances are, all marriages from all cultures, all classrs and all history of humanity is boiled down to a ritual that creates an deep intangible connection between people.
The connection can be for good, neutral, or evil reasons.
The question then becomes what is the purpose or point of that connection?
There you can find your answer. If you are honest with yourself.