What starts with sniggers and hilarity often ends in tears.
The news that Michael Douglas and Catherine Zeta Jones are taking time out from their marriage can only be greeted with regret.
After all, despite all the jokes about dirty old men and Hollywood gold-diggers, they survived for 13 seemingly happy years together.
Their longevity put the cynics, with their cheap sneers, to shame. But then Douglas in particular has always brought out the worst in a particular kind of male commentator. That's partly due to the fact he's not only a star, he is a genuinely great actor. And of course their loathing only went into overdrive when he won the heart of a woman 25 years his junior.
Despite the age difference, Douglas and Zeta Jones seemed well matched, with each complementing each other. The scion of Hollywood royalty and the girl from Swansea, their story was like something from, well, the movies.
Both – despite the distorting mirror of fame – seemed genuinely affectionate and at times cosily domestic in their love for each other. Have a look at the endless footage of them and their children on YouTube: there was nothing fake about their romance. Both were also honest, pragmatic and bravely public when confronting serious illnesses: in his case throat cancer, in her case being bipolar.
Over the years, we've come to respect them, admire them and even – whisper it gently – think rather fondly of them.
As we all know, in love, as in life, sometimes things just go wrong. Maybe the pressures of living in the public eye took their toll. Undoubtedly, their illnesses piled on the pressure.
Despite all the speculation, no one knows the 'real' story behind the split. The tabloids may wish for lurid sensationalism but I suspect most of us can't help but feel just a little bit sad at the end of an odd and, oddly endearing, love story.
Let's hope that perhaps there might yet be another happier twist in this Hollywood tale.