There is not much to understand; it's more about feeling. It isn't really about the individual verses a merciless society, but rather, the divide that society juts between two partners as a punishment for their desire to disobey society. I'd like to think, or maybe we would all like to think, that when we find our "other half" we can overcome all the hurdles in life. The two of us together is infinitely stronger than the mere sum of our individual strengths.
From the beginning you can feel the tension in the couple's relationship. From the beginning you know they aren't happy. And the little time the film devotes on their happy beginning gives you the feeling that the romance is long over, and its brevity a reminder of how exaggerated romance is in our collective psyche. The reality of working for money, of children, of doing your share of a marriage, and other aspects of this cruel reality dominates the movie.
"Cruel"? Only so if you only think of marriage as love. There is no love. When that word is mentioned anytime in the movie, it is woven in tension and even absurdity. Love gets you to believe life is possible because it opens up the possibility of having another person in your life. Love could also mean letting someone else do the work of fixing your problems instead of working on it yourself. Throughout the movie you feel that the two are dying to reconnect but fails at every attempt, partly because one is dying to make the other person give something no one in the world can give so readily, such as constant attention or space and understanding. And the resemblance of a connection, or just harmony, simply emphasizes the useless effort in the pretense, the fairy tale.
When the couple actually implements the steps to realize their goal, you almost feel that maybe things might just be OK and you wonder where the movie will go from there. You only feel like this if you are one of the few who still hold out hope for love, for marriage, for two people becoming infinitely more powerful than the sum of their individual strength. But it soon becomes obvious that society has a strong arsenal of weapons to deal with those who believe they can flaunt its rules. And without these rules, and the hesitations and doubts they cast in the heart, you might actually see the truth of what you need to do in life. That psychiatric patient, however annoying he might be, you feel he is the only sane person in the whole movie because he is the only one who can see the truth, and we also see the truth because we aren't constrained inside the movie, inside the story.
We need to live with others, but we need also to be who we are. We grow up with the mixed message that we need to be who we are against peer pressure, and yet we cannot upset teachers and parents. The real deal is that we can be who we are within the limits of authority. We cannot bow to pressure for drugs because drug dealers are not society's authoritative figure, but we must do as the police requires, otherwise, society must actually be, different.
You can feel the strangulation of April, slowly, not directly by society, but by society through her husband. She hates him only because he is the periscope through which she sees and interacts with society. She is a brave woman, defiant, as the psychiatric patient notes, but she is not more powerful than society's immense pressures. In the romantic world, you wish that her husband would be more supportive and stand up with her. But why not wish that she be more understanding of his plight, of his temptations, of his weaknesses; without this understanding she can choose either to continue her strangulation or leave society, leave him. But she opts a third option.
Back in the fifties people got married young, when they thought that they knew enough about life and love was the only reason to form a union. Even then life was very complicated for those who refused to blindly do as society asked, even though all it asked was for you to be bored to death and do what you don't want to do. It did not ask you to sacrifice your life, to starve, to be homeless; it merely asked that you give up your dreams and be someone else in order to fit in. Pursuing your dreams is dangerous and if everyone did that, it would be a very unstable society we live in. April, having little success with her own acting career, wished for a better future for her husband. He, of course, works in an undesirable job in order to bring happiness to the family. Two people wanting to love each other, but it simply doesn't work out because love is not enough and the immense list of things missing makes love seem almost preposterously unnecessary.
You'd wonder if people would love their spouses more if they were allowed to be who they are. If they were allowed to pursue their dreams. The film doesn't discuss much about the other reason people disconnect and fall apart. That is their own individual baggage. But perhaps it is implied that Frank's inability or weakness to go beyond where society put him, which is where his father was, is part of his baggage. He may have dreams, but like most people, he is afraid of realizing them. What about the dream that you will love your wife forever? Isn't that even scarier to realize?