Last weekend, at a family wedding in the country, I was overwhelmed by an emotion that has, in the last year, become only too familiar to me. Sitting in a stifling marquee, listening to my cousin Sally's husband making the traditional father-of-the-bride speech, I was overcome by a feeling that was part envy, part guilt and part regret.
My cousin's marriage, which has lasted for 25 years, is by no means perfect - what marriage is? - but against the odds, she has achieved something that is now, and always will be, beyond my grasp. As I looked at her sitting happy and radiant at the top table, laughing uproariously at her husband's far from funny jokes, I realised that, in a world that has horribly devalued the institution of marriage, she was reaping the benefits of putting the love and security of her family first, before any disagreements she might have with her husband in the rough and tumble of daily life.
Watching her united with her husband on such an emotional occasion reminded me sharply of exactly what I had lost - but had no idea I was losing - seven years ago, when I got divorced from my husband, the father of my three children, after 25 years together.
Our relationship had broken down, I can now see, not because of any petty irritations such as his lateness or my untidiness, but because we had both moved irrevocably away from each other. In the past few years of our marriage, I was more absorbed in my children and my career than I was in my husband while he, feeling increasingly isolated, simply switched off.
It's a scenario that will be familiar to many couples. But how many of them choose to separate, and how many have the gumption to stick it out?
The trouble is nobody tells you the truth about divorce. They tell you it's a 'difficult' experience, and it's generally accepted that the process sits somewhere near the top of the ten most stressful life events. But in the main it is regarded by society as a necessary evil. A milestone which, in an age when two in five UK marriages will fail, millions of us will go through at some point in our lives. Indeed, in many ways, divorce is given a more positive spin in our confused modern world than marriage is.
The drawbacks of divorce are believed to be mostly either financial - as if the splitting up of the spoils of a life together were the very worst part of the process - or the fallout experienced by the children. Little is ever said about the longer-term effects of divorce on the couple. No one ever points out that the repercussions of a marital split will reverberate down the timeline of your life forever.
This week, the Conservatives published a report commissioned by Iain Duncan Smith which proposed a three-month 'cooling off' period for couples considering divorce. But the idea that couples would be ready to rethink their break-up after such a short period is unrealistic. As I have discovered the hard way, it is only now, seven years after I received my decree nisi, that I am starting to realise the gravity of what I have done.
If it has taken me this long for the seismic shockwaves of divorce to really hit home, how are warring couples expected to take an informed decision about separation when they are in the midst of the rows, the tension and the recrimination that so often accompany the death throes of a marriage?
It is only now that I am experiencing something akin to the seven-year 'itch' of marriage; the seven-year 'ache' of divorce, a regular recurrence of the emotion I experienced at that recent wedding - a pang, a regret for what has gone for ever.
There is much in my post-divorced life that I am grateful for and happy about. I have gained a new partner and two stepchildren, and our 'blended' family is more harmonious than anyone could have expected. My ex-husband, who is a media consultant, has 'moved on' to a perfectly ordered and elegant bachelor apartment and a social life (with a series of ever-younger girlfriends) that is the envy of his old married friends.
On the surface, we have 'come through' our split relatively unscathed. But however contented I might be with my new partner Robin - and he with me - we realise that our relationship is, well, somehow second-best. Our true loyalties lie not with our new 'blended' family, but with our own biological children and the ex-partners from whom we were both amicably divorced.
The important occasions in family life which I used to love - birthdays, Christmas and so on - are now difficult, trying times. They are unsatisfactory no matter how hard we try; whether my partner and I attempt - as we have on several occasions - to unite our new and old lives or agree to simply be apart for the 'sake' of our children.
Now, for example, we spend Christmas apart - each ensconced with our children and ex-partners - which causes huge tension between us and has made us both dread the annual celebrations. When my husband and I parted, my view of divorce was simplistic. I believed in the notion of divorce as a clean break and imagined a 'fresh start' would solve all my problems. It wasn't a decision made lightly, but I had no idea of the true complexity of unravelling a life that had been led in tandem with someone else for more than 20 years.
It was the death of my parents, within six months of each other in 2008, that was the catalyst for my change of heart. At my father's funeral, my brother made a moving address about the formidable achievements of an extraordinary man. He concluded that the greatest achievement of all was his remarkable partnership - over 60 years - with my mother.