Martin gets Alzheimer's disease and as the disease worsens later in the film he has depressive episodes and sometimes behaves disrespectfully and/or violently towards Barbara.
in one scene Martin and Barbara are swimming in the water just off a beach, Martin begins to have difficulty swimming, he disappears underwater before surfacing and dragging Barbara underwater with him. they are seen sinking for a few seconds, but both are rescued afterwards.
Martin shoves Barbara at one point when she tries to stop him from wandering, he no sooner after this breaks Barbara's violin, she becomes very angry and slaps him repeatedly.
the most violent scene is at a birthday party where Martin is seen urinating on a plant and when Barbara tries to stop him, he then begins to grab and beat her repeatedly. he has to be restrained and forced into submission once by others and again after a doctor arrives and he is given a tranquilizer shot.