This is a very difficult question [...]
Have you read HG Wells'
The Country of the Blind? It's the same idea.
I haven't read it but I know of it and understand how it relates as an allegory for what you're saying about our society shaping our surroundings and perceptions.
Your post affirms for me what I was saying about the nature of love. The only places we really see this is parent/child and some other relatives. To drop your ego in a relationship is equivalent to the old cliche about being willing to lay down your life for that person. For most of us we never really understand that feeling until we have a child. Many people claim it with their partners, but I doubt its as common as we portray. But realistically that's ok because we are very rarely placed in a position to make that ultimate ego sacrifice. For children we are, even if it is only in terms of superficial sacrifices but raising a child requires a different protectiveness. For our partners, simply investing in them is good enough. That investment ensures our continued ego involvement and willingness to sublimate some of our desires for the needs of a partner and offspring.
The thing is, the only time you can forge such a genuine relationship with another man/woman is by having a child. Most of the people I recognize in good marriages have truly taken an attitude of putting the relationship and their investment in life and child rearing ahead of their ego investments. So you're right, in a sense. But we still display a proclivity for investment and commodification. When you strip away the romantic trappings, that's all our relationships amount to at the heart.
What gets lost in the modern age is that our interpersonal relationships
shouldbe an equivalent investment to bearing and raising children. Those who can actually stay together for the children understand this and form strong bonds. And I don't mean like the bitter "staying together for the kids" cliche, but rather putting the family unit (mother/father/children) as a collective in front of any individual in that system for the good of them all. We have a hard time doing this with a simple dating or hook-up relationship because it lacks true investment. Sex itself is an investment of the highest biological order because it involves a co-mingling of our greatest resource, our genes. That same reason we will die for our offspring
shouldbe a reason to invest in relationships. We sublimate it, hidden subconscious biology melds with conscious front brain ego rationalizations and gets expressed as a form of investments, resources, risks, rewards, transactions and territorial pissings.
I suppose its a problem of chicken and egg. I'd say its more likely that all of society and economy has formed itself in the image of the biological imperatives for survival and reproduction that our brains shuffle from hind to front every moment. You say that society has affected how we approach our biological side, but what is society if not an extension of our own thoughts and desires? It seems the height of intellectual hubris to me to assume that we have devised these inhuman systems that are so inherently powerful as to override and influence our most basic biology.
No, I would say our society is fully formed by how we approach ourselves, our environment, our lineage, and reproduction itself. We focus on transactional ratios because that's always how we know if we are wasting our resources. In biology genes are money. Sperm is cheap and eggs are expensive. You have to accept your place in that to understand how to best leverage your self for relational success, which equals reproductive success, which is the imperative driving every one of us as mammals. The problems we run into are largely based on a culture that technologically doesn't need to to reproduce any more. Thus there is no investment, your currency is without backing and standard, yet you are still driven subconsciously by the value of you and your mate's potential contributions to the gene pool despite consciously opting out of the system driving your desires.
You're correct, true loving relationships are pretty rare. There's little reason remaining now to invest that heavily in only one other human. You can do it for a time, but eventually your returns will be more optimized with another investment vehicle. Failing to recognize that reality leaves one or both partners feeling ripped off because they didn't adjust their expectations for long term performance and rearrange their assets appropriately.