I think that there could be a couple of ways to proceed with this question. I feel that the film does affirm moral behavior. The characters come to moral realizations that are more elevated than the moral positions they possess at the start or middle of the film. For example, Lester understands his true function as a husband, father, and neighbor in a better light at the end of the film than at the beginning. Carolyn understands her function as a wife and mother better at the end than at the start. Jane recognizes her own moral stature as daughter and girlfriend in a better light at the end than at the start. Even Angela gains greater moral insight into herself and her world at the film's conclusion. Moral behavior becomes a journey for each of the characters, something in which there is struggle and confusion as well as a need to work, no different than the cultivation of the American Beauty roses that grow in Carolyn's garden. In this light, the film makes the clear determination that the struggle to be "moral" is something that individuals must absorb for themselves and fully grasp and understand through experiences and the use of freedom.