I like to think that part of the message behind the movie Submarine is this: you could never know the full extent of what your actions do to another person until it's done and you look back on it. Considering it is wholly about adolescent nievety and the prospect of loving ideas rather than reality. This comes as no surprise.
This could be backed by the symbolism shown in the scene where oliver talked about ultrasonic frequencies.
“Tonight I stumbled across an encyclopaedia entry on ultrasound. Ultrasound is a sound vibration too high frequency to be audible. It was first developed to locate submerged objects – submarines, depth charges, Atlantis and such. Some animals, like bats, dolphins and dogs, can hear within the ultrasonic frequency. But no human can. No one can truly know what anyone thinks or feels. What’s inside Mum? What’s inside Dad? What’s inside Jordana? We’re all travelling under the radar undetected. And no-one can do a thing about it.”
This is in reference to one's feelings and interpretation of the world around them. You never know what's going on inside someone's head until it comes back and smacks you in the face.
Oliver's father didn't understand that being impartial and distant was putting a rift in his marriage. Oliver's mother didn't realize that her constantly going out and bringing Graham back into her life, being unfaithful to Lloyd, would effect Oliver's mental health and such (even though she, ironically, had been overzealous in her concerns over his mental health.) And Oliver didnt realize that all of the time he spent worrying fruitlessly over his parent's situation was time that he could have been there for Jordana. Instead, it was spent trying to repair his parents relationship (which wasnt going to change even with his intervention).
Also, in the scene where Oliver is having Christmas dinner over at Jordanas family home, Jordana's father started crying in the background where Jordana and her mother go comfort him while Oliver is left alone at the table, back facing the situation. This is symbolic of his blind eye turned to the fact that his parents aren't the only ones having family issues, but he doesn't realize because he is too caught up in it to notice.
It's the next scene where he and his father are both expected places on Friday. Oliver is supposed to visit Jordana and her mother at the hospital, but stays home and ignores the phone call. His dad stayed home when he was expected at Grahams speech with Oliver's mother.
Also, I would like to note that when it's mainly focused on Oliver, the screen fades to blue. And when its mainly focused on Jordana, it fades to red. The movie is color coded. This is symbolic of Graham as well, since he is constantly mentioned as talking about aura and color n' that jazz. Oliver, after having seen Grahams film says that if his dad radiated a color, he would be ochre or egg-shell.
