Even though it might sound like a contradiction in terms, change has been one of the few constants in British family life over the last few decades.
Despite a slight increase in the latest tally of couples opting for marriage, such figures have seen steady decline since the early 1970s.
A small recent rise in the number of divorces has also not been able to mask an overall decrease since it reached a height 20 years ago.
Over that time, the family structure has undergone something of an accelerated paradigm shift. In 2005, the first civil partnerships were allowed, a development which was followed by same-sex marriages in late March this year.
In addition, last year there were 700,000 more cohabiting families than there had been just a decade before.
Choosing to live together but not marry does not, of course, provide a cure for the tensions which can undermine relationships of all types.
However, married couples at least have a process to apply to their breakdown. The Matrimonial Causes Act of 1973 gave a structure to how joint assets might be divided as well a framework for the provision of maintenance for spouses and children alike.
The Act was very much of its time and did not - or could not - foresee the radical change within the family unit which would occur in the following years.
It did not offer cohabitees a formula to cover what should happen in the event of their relationships collapsing - with or without children. Forty years on from the Act taking effect, unmarried couples in failed partnerships who do not have a cohabitation agreement in place are often left to resort to property law in an attempt to resolve any differences.
The reality contrasts with the belief which many people hold about the length of relationships providing some entitlement to a claim on assets or maintenance - the persistent myth of the "common-law spouse".
Financial provision is really only available to married couples or - more recently - to those taking out civil partnerships. Given London's status as "divorce capital of the world", the disparity between the rights of the married haves and cohabiting have-nots has been brought into sharp relief.
That contrast has, in part, fuelled recent attempts to bring the law into line with the shape of the modern British family. Last year, the Liberal Democrat peer and family law barrister Lord Marks QC introduced a Cohabitation Rights Bill in an effort to provide cohabitees with a measure of protection.
Yet more momentum has been generated this week by the comments of Sir James Munby, the President of the Family Division of the High Court.
In a speech to fellow lawyers, he described how women who had given up careers to raise children in unmarried partnerships which then failed were effectively "thrown on the scrapheap".
Reform, he argued, was "desperately needed", adding: "It is inconceivable that society will not right this injustice in due course".
What he proposed was to "uncouple" the process of divorce from that of arranging financial provision at the end of a relationship, so potentially enabling others, such as cohabitees, to receive support - something which is, in my opinion and that of my colleagues, a bold, refreshing and fair step.
He also called for "no-fault" divorce as a means of simplifying separation and reducing the possibility of tensions during the process.
Different branches of the media and the law have seized upon elements of what Sir James had to do and, certainly, his comments on cohabitation have caught the eye of many people.
Even so, I believe his remarks amount to a wider appreciation of the pain of relationship breakdown for people regardless of their marital status.
The uncertainty about what will happen to those individuals who have been in unmarried partnerships only adds to the strain and really helps no-one.
As any family lawyer knows, change in the law to meet change in the home is long overdue. The Law Commission, Lord Marks QC and now Sir James Munby have all raised their voices in favour of new legislation.
The question of whether their demands will be met rests with the Government.
Their deliberations will be watched with interest.