I think that the film version of Sparks' work demonstrates the challenges of love in different stages in life. The early conception of love is one in which there are social challenges, emotional challenges, and seeking to properly understand and control the sense of passion that exists in the young lovers. Noah and Allie's love is filled with the challenges of being able to sustain love of another with the love of oneself. How characters navigate the challenges of achieving their own dreams separately as well as the dreams of one another together is one of the distinct elements of the youth in love. This is seen in Allie's acceptance into college, and the hurt of Noah to say that he is happy for her in the accomplishment of her dreams. Such an idea can also be seen when Noah describes the dream of rebuilding the house with Allie asking if she is able to have a say in such a vision. The scene when both make love highlights this, as both struggle to understand their own needs and sensual desires with that of the other. When Allie must make the choice of whether to remain with Lon or to be with Noah, it is the pinnacle of how young people in love must straddle the world of their own sense of identity in merging with another.
As this pivots to the older vision of love, the challenges of youth have been supplanted with ones of age. Passion and sense of self have become understood in the love of another. The challenge that is experienced is how one maintains a love and a commitment with the ravages of time, specifically in the form of Alzheimer's Disease. The entire premise of the notebook is shown in the film as a logical response to the destructive capacity of Alzheimer's. The idea of "I will come back to you" is where the pain of love in the older stages of life is evident. Noah struggles with the fact that his entire premise exists on fighting the degenerative condition of Alzheimer's and seeking to reclaim, if only for a moment, a lifetime of love. When Noah tells his kids that he wants them to have the house, he says, "My home is with your mother." Such a statement is a pivot from the insecurity and fear of youth. In its place is a different kind of fear, one of abandonment and emptiness after a lifetime of connection. The film shows this best when Allie and Noah dance and she asks him, "How much time do we have left?" It is said in the context of her remembering him, but moreover, it indicates the challenges of an older expression of love, where emotion is secure but time might not be. The look of horror that Noah has when she slips into panic is one that is more than just that reflects that moment. It is a reflection of the condition of being old and in love, when mortality becomes finite and one can see an end with real and definable features. This is not the same insecurity that was experienced as a young couple, where the moment was always seen as something elongated into an uncertain future. Now, this moment is the uncertain future, for an end, one way or another, is inescapable. Its implications profound, the true embodiment of a lifelong commitment is shown in the final scene between Allie and Noah when both hold one another saying "Good night" and convinced that their love has the capacity to withstand time, even if their bodies and mind will not do the same.