Terence Blacker: Why is it so hard to say goodbye?

For reasons no one quite understands, film directors have lost the knack of the satisfactory ending. Films tend to continue well after their natural ending, according to the actor Samuel L Jackson, who cites Spielberg's latest, Lincoln. Some meander, others go off in a new direction, or close with modish, irritating ambiguity. Ben Affleck, another Hollywood man, has blamed the need to pitch film ideas. "The thing about a pitch is that it does a great job figuring out the first and second acts, but no one ever sits down and works out the third act."

Take these words away from the world of film, and they help explain many reasons for contemporary unhappiness. At work, in love and in life, no one has worked out the third act. It is a good moment in the calendar, just as things are starting, to consider the art of ending. If only more in life could close like the old year – a drink, music, maybe some fireworks, a hug or even a snog, and then it's gone.

We have been brain-washed into believing that what matters are the relatively easy stages of experience – the hope of January, the energy of May, the pleasure of July, the nostalgia of October. We prefer not to think too much about December.

Admittedly, conclusions tend to be tough. Only the exceptionally adult can end a serious relationship with a shared admission that what was once good is now something else, that it has simply run its course. Instead, there is blame and bitterness, a looking back at a history now poisoned by failure.

At work, even the most civilised and well-planned parting of ways tends eventually to be accompanied by an expected sense of anti-climax and disappointment. There are few good professional farewells.

It may be seen as a weakness, in a culture obsessed by dynamism and success, to be prepared in advance for the moment when something ends. We believe ourselves more likely to succeed, if we remain blinkered by expectation and hope. But knowing how to close a show with dignity and generosity is one of the better tests of maturity and character.