It was also said, "Whoever divorces his wife, let him give her a certificate of divorce."
But I say to you, that whoever divorces his wife, except on the ground of unchastity, makes her an adulteress; and whoever marries a divorced woman commits adultery.
This made sense in 1st Century Judea, where the social and economic situation of a divorced woman was worse even than in our times. Church efforts to enforce it legalistically, of course, have been a cruel disaster (and sometimes farcical, as in US States where people were sometimes driven to fake an affair just to escape a bad marriage.)
There was also the fact that divorces exacerbated tensions within families and tended to break up communities. [One private suspicion... When I used to ask 'Why did our Meeting split off from ___?' I'd be told that our Meeting had been organized for the convenience of a group of people living closer to here. But it looks like one of our members had married a woman divorced by one of their members, around that time... and since then, having two Meetings in the same town has made it easier for formerly-married couples to both attend Meeting without having old wounds rubbed.]
Anyway, in current times, is this still relevant to making our way more closely under God's wing...? as seems to be the purpose of these pronouncements?
With courtship behavior & close physical contact, there is a serious risk that close emotional bonds will form. Quite apart from any sort of ceremony, tearing oneself away from such a bond can leave a life-long, unresolvable pain.
Aside from that, such a connection feels risky, no matter how much a person will want exactly that, when it's worked out badly for them or for their parents in the past.
'How this has worked out', in modern times, will often include experience of divorce. But there are also the horrors experienced by and perpetrated by couples who 'stay together for the sake of the children. So far as children are estranged from their parents -- as is probably typical these days -- they will tend to recreate their situation, whether by choosing partners too much like or too much unlike whatever they're used to.
People are also often attracted to potential partners who embody qualities they lack. That can make for a very practical alliance, in which 'Both of us together add up to one competent human being' [as my wife sometimes puts it], but it can also make for serious conflict.
When someone lacks a quality, there's a very good chance he's been suppressing it in his own personality. He may initially be impressed to see the other person expressing this so freely -- yet over time, start sniping at its manifestations in them. Divorce and escape from that kind of relationship can make for a glorious feeling of liberation (as I found when my first wife kicked me out.)
But unless something more significant changes, then [as Fred Neil used to sing] "Same thing gonna happen again, cause that's the bag I'm in!"
Any rule about this, with people as we are today -- needs to be interpreted as Jesus interpreted the Sabbath rules, in light of the fact that the rules are made for our sake, not the other way around.
There is nothing better than having blundered-and-been-led at long last into marriage to the right person! But my ideas, about what 'this right person' should be like, turned out mistaken in many ways. Leaving my first love, because she hadn't matched those ideas, was a terrible mistake, leading to my first marriage to a good woman (a horrible mismatch!) -- which then led, eventually, to that 'right person'. Life and love transcend anyone's rules... but the spirit behind them can guide us in each specific case.