What do we know about love? It is this ethereal substance that we are in search of in our lives. It's mercurial. So days there seem to be more of it than others, but at the same time the more you try to hold it the faster it runs through your fingers. Rorschach doesn't believe American love exists anymore, and if Laurie and Dr. Manhattan are an example of American love then maybe it doesn't.
Love transcends time
We see Dr. Manhattan both find and lose love. He meets the love of his live as a man before he becomes a superhero. He is the perfect picture of success. He is the best in his field. He has a beautiful girlfriend, who is also amazing in her field. He has love, success, and a future. This is however, not how the story plays out. Love does not have such a simple path.
John is not destined to love easily. His humanity is taken from him, though this appetite for sex does not disappear. He is very much a man. He is very much human and yet he is constantly forced farther away from humanity. Even though all he really wants is to be loved and to help those he cares about feel loved.
Around and around we go
The same moment happens to Dr. Manhattan multiple times.
Dr. Manhattan exists both inside and outside of time. The biggest problem for Dr. Manhattan is that love is timeless only in a linear fashion. Dr. Manhattan is omnipresent, though not omnipotent. He doesn't know how to exist because he is a man thrust into the existence that is not human.
Where we stop nobody knows