Imagine living with a man or woman who you are not married to. Despite not being married, you contribute (in cash, comforts, emotions, time, personal sacrifices, etc) to the home, to property, to entertainment (including sex). Then you break up. If you were married, somebody would be entitled to alimony. Shouldn’t you be awarded a financial payment for your investment in the relationship, especially if your partner has become successful in life because you were there to support? You only get this money if there was a contract - written or oral.