The irony of silence
Since the main character in the story is mute from post-traumatic stress, the novel is the only communication she has with the outside world. To her friends and family, Marina is silent and closed up. But to the reader, she is a confidante. She says so much for a girl who doesn't say anything at all.
The acid attack
What is Marina going to say to her father? "Oh, it's okay, I know it was an accident." Not quite, because that acid attack was intended for her mother. This is ironic because even without the tragic twist where Marina is wounded, it's already bad enough, because Marina was going to witness an act of horrifying abuse against her own mother. This is a difficult reality to face.
The irony of friendships
Talking seems like a prerequisite for friendship, but Marina shows that you don't have to be attractive or interesting to be someones friend—you just have to behave friendly toward them. Marina is disfigured and silent, but she is not a pariah, because she is humble enough to make friends in whatever way she can.
The irony of human evil
Humans are the best part of the story. Look at Mr. Lindell who enables Marina to cope with her difficult life through journaling. Or the patient friends who accept Marina even though it's difficult for them because of her disfigured face.
However, humans are also the worst part of the story. The inciting incident is a violent act so cruel that when Marina turns back to loving her father, the reader might even cringe, because Marina might not be safe with such a violent, angry person. And yet, Marina's undeniable love for her father is already aware of this, making her love greater.
The irony of the ending
When the daughter says, "Hello, Dad, I've got so much to tell you," it's the highlight of the novel, and it's very ironic, given that the daughter hasn't spoken a word since, and also given that the father is the last person the reader would expect her to want to talk to after what he did to her.
