Surely since human beings were created and punished with the sense of... love, they've also coexisted on their own terms and conditions all along. At least, most of them. So why do we need a formality for it?
Back in time, marriage was powerful. It was based on a more political and social important ground rather than feelings, emotions or compatibilities. Before, a marriage wasn't representing just an union of two persons but a union of kingdoms, warriors, manpower, political relationships benefits and wealth. Or just an union of legacies meant to be preserved and flourished in order to secure a better living/survival of their own genetic material- next generation.
Most of these scenarios were reaching an even more successful result when the couple was compatible on all levels: intellectual, social, parental, financial, sexual and more importantly emotional or spiritual level. Hard to envisage all of these as most of them were seeing each other for first time just right at their wedding ritual.
Of course a disputed part of this example involves religious practices, different social classes and times.
Nowadays, excluding the exceptions, it really seems happening the opposite. We fall for feelings first, we get married and then we try to figure it out the rest, in a formula of two. Or even more frequently, we don't marry at all, we coexist and adapt to the system as we please and enjoy the sense of freedom in an unofficial marriage. After all, why should we do it?
Well, firstly, why not?
The natural form of living within a modern society, it shows that since we're born, we're given a birth certificate. A social proof and track of our existence in the society. Same we get when we die. Optional, during our lifetime we get different profesional statuses and certifications as proofs of our social/professional integration or personal aspirations. Therefore, naturally speaking, a social form of our existence in a new created family context could be issued. Essential to mention that it must happen at the right time and moment, agreed. Each partner secured on their own emotional assets towards each other as a fundamental base of living in two, starting a family and must have self determined to commit towards marriage concept and it's evolved aspects: individual, partner, spouse, lover, parent, professional, grandparent, etc.
Regardless of the involvement of a child or not, we all need each other's constant love and support during our lifetime. Love and commitment is key and since we've the most evolved creatures of this planet, how comes that we seem to not be able figuring it out how to happily share a communal space or lifestyle and loving each other, forever? At least, until time decides so. And then you can say that at least you've tried. The same as you've taken an exam. Except here, you'll be both emotionally and intellectually involved with lots of tests to take all the way.
We all, as human beings transform individually along time. We discover new layers of us, at different stage of life from birth until death. By the time of a new layer being processed and taken place within us, our mind, body and spirit are put on trial towards ourselves first and to others around us. Ultimately, in the process of those stages, while both of you struggle to digest it and pass trough, even the deepest nerves are stretched and feelings might just seems to fade away in that coexisting formula. In those delicate moments, all it needs is awareness of our mental health and overall well-being, strong and efficient communication, an open minded approach and continuous commitment of self and familial value, willing to learn how to work it out in the future. Like that, surely the best results and emotional satisfaction you'll get back with time. When all of these seems unreasonable due to a massive lack of love towards each other, then separation/divorce might be a better solution of being happy afterwards.
But here is where marriage should play its role. Although a legal form of agreement (and a spiritual one when is performed within a religious ritual as well), It's truly meant for you to remember that commitment promised and it should give you some subconscious motivation to stick to it at its best and worse. A formal reminder to not give up easily on that feeling that connected you both since beginning and to try and make it work . Again and again.
Even today marriage is powerful if you believe and make it so.
As far as the financial reason concerns, can be simply put aside, excluded from the marriage agreement with just another form attached since beginning. It's only left a religious motive or other more legal sensitive subject that can influence a marital decision. Maybe too sensitive to all of us to understand and be discussed.
In the end of the day, each marriage/ family is unique and strongly shaped by its own members or lifestyle, believes and mindset. And we must all appreciate and respect that when comes to judging, interfering with others. Give a healthy advise, support if you can but the rest of your concerns and focus should be towards your own personal life/marriage.
Overall, it might sound all good and healthy to have a general family name that you've created socially in your lifetime, which connects you to all its members and all together as a whole....but more importantly and beautifully should be the existence of the loving family and powerful sense that keeps you all together forever with or without a stamp on it.
Believe in love and rest will follow.