What is the law on enforcement of contract between married couples

The law on enforcement of contracts between married couples is that, such contracts are generally unenforceable. This is because the law presumes there is generally no intention to create legal relations. This on the authority of Balfour v Balfour

However, where such an agreement is made between couples who are separated or pending a separation of couples or where such an agreement is to cater for such separation between the couples, the same will be enforceable as a binding contract as between the couples. Authority being Merritt v Merritt