Marketers, agencies and the 30-year itch

Levi Strauss and BBH have parted ways after their three decade long relationship; Saatchi & Saatchi and the Singapore Navy after 28, and now Harley-Davidson speeds off with 10 other agencies, leaving creative agency Carmichael Lynch in the dust after a 31-year relationship. What is the trend with old relationships ending? Is there a really 30 year itch with marketers and agencies and if so, what is causing it? Visiting Professor of Marketing Chang Dae Ryun gives his take.