Tony and Veronica Only Have Sex After Breaking Up (Situational Irony)
Throughout his relationship with Veronica, Tony is sexually frustrated because Veronica doesn't want to have "full sex" with him. After months of bringing her to climax by letting her rub against his wrist, Tony breaks up with Veronica. They then run into each other at a pub and go home together to have sex for the first time. In this instance of situational irony, the thing Tony wants most from the relationship only comes to him after they have broken up and the power dynamic has shifted.
Adrian Dates Veronica (Situational Irony)
After Tony and Veronica break up, they run into each other occasionally but there is no apparent acrimony. However, a few months later Tony receives a letter from Adrian informing him that Adrian has been seeing Veronica. In this instance of situational irony, Tony realizes his ex-girlfriend has "traded up" to the friend he most admired in high school. Rather than being gone from Tony's life as he had believed, she hurts his pride.
Veronica's Mother Leaves Adrian's Diary to Tony (Situational Irony)
In the second half on the novel, Tony learns that he has been named in the will of Sarah Ford, Veronica's mother. To his bafflement, Sarah has left him Adrian's diary, suggesting he may find it interesting. While Tony is intrigued, he doesn't understand why his ex-girlfriend's mother would have something that once belonged to his high school friend, and he cannot fathom why she would think of giving it to him. In this instance of situational irony, a person Tony only met once treats him with far more significance than Tony believes to be logical.
Veronica is Actually Adrian Junior's Sister (Situational Irony)
At the end of the novel, Tony once again goes to the pub where Adrian Junior and the other developmentally disabled adults are regulars. When Tony's presence disturbs Adrian, the care worker comes to Tony's table and starts a conversation about how Tony knows Adrian and Veronica. In an instance of situational irony, Tony learns that Veronica is not Adrian's mother, as Tony had believed, but his sister. With this unexpected revelation, Tony realizes that Adrian impregnated Veronica's mother before he killed himself.