Watching Marriage on the Rocks, one wonders why Frank Sinatra bothered taking on this project, a question one asks when viewing many 1960s Sinatra films. The actor clearly has no interest in Marriage, other than perhaps a paycheck; while it's true that the part itself is no great shakes, Sinatra could at least try to find the energy to make something of the part. Instead, he drifts lazily through the film, turning in one of his most boring and unaccomplished performances, and hurting a film that already needed a considerable degree of help. Not surprisingly, there's no chemistry between him and Deborah Kerr, who at least attempts to do something with her character. Kerr is fine, but she's not really a natural for this kind of film, unlike Dean Martin, who gives Marriage almost all the life it has. Martin clearly is enjoying himself, and his joy is infectious. It's not great acting, but it's precisely the kind of performing that is needed to get Marriage off the ground and keep it spinning. He can't make the script's contrived, convoluted plotting believable or cause the flat dialogue to sparkle, but he does make things lively.