The law allows a person to seek a financial settlement from their partner following a split. A court can make orders if necessary using a catalogue of complex rules laid out in legislation and developing case law in the courts.
One of the most important points that many people do not seem to realise is that the law does not make a link between who was to blame for the split and how the assets should be divided. It is completely irrelevant and is only important in issues relating to the actual grounds for divorce and, potentially, decisions relating to child residence and contact issues.
Every case is different, but basically the law requires all assets and liabilities acquired from the date of marriage until the date of separation to be valued and subject to some form of division between the parties. But in certain circumstances properties bought before the marriage can still become part of the calculation. Some assets and liabilties are or can be potentially excluded from this calculation, such as gifts individually received or individual inheritance proceeds. Sometimes if one person in a marriage has been reckless or dishonest with money or assets through (for example) gambling, alcoholism, secret spending on "paramours" (people they are having an affair with) or other inappropriate expenditure, then any effect that has had on the value of the assets of the marriage can be offset in favour of the other person. This is one of the rare examples of the law attaching blame to financial division in divorce situations.