When you’re in a serious relationship with someone, you may start spending each other’s money and sharing each other’s property. If you split up later, it can be complicated to figure out which property each of you own.
Another problem is that often, especially if you have children, one of you might be working and earning money whilst the other stays at home to keep house and look after the children. It wouldn’t be fair if the person who earned the money got to keep it all, while the person who worked to look after the house and children didn’t get anything.
Because of these problems, there are laws that say how the property will be divided if a serious relationship breaks up. Generally, all the property that either of you had accumulated during the marriage gets split in half when you split up.