A couple of reasons, all connected.
In short: everybody wants to receive help, assistance, appreciation, affirmation, friendship, love, fair treatment, consideration, and probably attention of all things. But nobody wants to give it, let alone to have an obligation to give it on a reliable, constant basis. We are turning into snowflakes, demanding unrealistic amounts of care and assistance on a non-reciprocal basis, while avoidng obligations, burdens, duties and anything else that’s not pleasant, profitable or rewarding.
Next, everybody is optimizing gains these days — maximum bang for the buck, maximum profit from minimum investment.
While you can have a purchase & sale or an employment contract that’s a sweet deal for both parties and perhaps the best deal they’re realistically going to get, you still can’t have he absolute best theoretically imaginable deal for both parties at the same time. Nobody wants to meet in the middle. Everybody wants to find a sucker, nobody wants to be the sucker. Or if not sucker, then I guess an extremely charitable, open-handed donor, sponsor, protector and otherwise benefactor. We’re living in a society build up of beneficiaries. Give and take — you give, they take.
People are blind to this problem because in addition to pride and ambition they are also lazy. So they won’t think this through until it’s late, perhaps too late.
There would be more marriages if people could have the assurance that the other party would neither want to nor be able to quit easily over a relatively trivial problem or upon the discovery of a better alternative deal. And again, everybody wants to receive this sort of guarantee, but nobody wants to give it.
Myself, I’m reluctant because while I don’t mind contributing my share or a bit more, I don’t want to be anyone’s sucker or a con’s prey. I don’t want to be the spouse who gets all of the responsibilities and burdens but none of the rights or benefits. I don’t want to be tied up in a marriage that exists only on paper. I don’t want to end up providing security and stability for someone who doesn’t want attachment or closeness. I don’t want to be in something the other party deep inside secretly considers to be only a trial or conditional marriage, which a lot of people do, though they won’t tell. A lot of people lie these days, when at stake are the stability, security and comfort that they crave. I certaintly don’t want to be anyone’s stepping stone for monkey branching to a more lucrative marriage option (after divorcing me). And I don’t want to hear, after some 10, 20 or 30 years, something like:
– I’ve never loved you, but I needed X.
– I’ve always loved someone else.
– I’m homosexual, I’m not attracted to you.
– I no longer feel female.
– I no longer want to be married.
– It’s best if we stop having sex.
– I don’t really want to spend time with you. I feel better alone, on my own, let to my devices.
… And so on and so forth. I’ll have none of that.