Grief is entirely individual, and the grieving person has to respond to their grief in a way that is relevant to them. How they respond may change over time. The difficulty with the platitudes detailed above is that they infer a judgement about how the person is grieving, the time they are taking over their grief, or how they are feeling.
Compassion is a funny thing isn't it? Human emotions are complicated and difficult to understand; sometimes we can barely understand ourselves, let alone others. Motivations and reasons behind our actions and behaviours and responses can intersect, and finding the true root of a problem can seem impossible at times. Often, it isn't the answer we expect.