Not all do though. As a common example, in a traditional/old-fashioned marriage where the wife is a homemaker and is largely under the thumb she might decide, once the kids have grown up and moved on that she needs to assert herself and reclaim her life.
Her husband pays her no attention so she has a fling and decides to call it a day on the marriage. This happens a lot (as does the situation where the husband loses interest in his long-suffering wife but that''s for another analogy) and what then happens is that the husband states that the wife will not get a penny of "his" money and proceeds on that basis.
The husband believes that he is 100% correct. When the court disagrees with him, it is obviously the law that is wrong. Clearly the wife having an affair disentitles her to any of the matrimonial assets as these are *his* to share with his wife and when his wife leaves, he doesn''t have to share does he?
This is a black and white example but a lot of cases pretty much tick all of the relevant boxes. The law moves on of course and has determined that each party contributes equally to the marriage whether this is through paid work, homemaking or sitting around all day doing nothing (if that is accepted by their spouse).
So, whilst the husband is wrong in law, he is morally right in his own mind.
I personally don''t care for the traditional model of marriage as it has too many flaws but I can understand how those who do subscribe to it fall foul of the law and would approach a financial case with completely unreasonable expectations without realising the error of their ways.
Of course, there are some people who will cut off their own nose to spite their face - *those* people need a slap..
You do raise a good point here and that is about those people who have no idea what divorce entails and the fact that there is no blame placed onto the ''guilty'' party in law. There are grounds for divorce but that does not mean one party being penalised due to the fact they have chosen to end the marriage, whether that be by adultery, unreasonable behaviour of some sort or another valid reason.
The other big assumption / myth is that the assets should be split 50/50 which as we know is not the case nine times out of ten. A similar myth to there being such a thing as a ''common law'' spouse and inferred protection for those who co-habit. Father Christmas and the Tooth Fairy don''t exist either people!
A sad fact is though that quite often, whoever behaves in the most bloody-minded and non co-operative fashion (or flat out lies) will actually get the majority of the assets in divorce / evade their responsibility to pay maintenance. I think we have all seen cases where that applies. An extension of that is whoever pays the big bucks for representation will also get a generous settlement. Money talks. I have personal experience of that sadly.