Christian's Discovery of Ana's Virginity (Dramatic Irony)
Christian assumes that Ana will not have experimented with BDSM sexuality before, but he takes it for granted that she has had previous sexual partners and has cultivated an awareness of what she enjoys. Readers, however, are aware that Ana has not had any sort of sexual experience before. Dramatic irony is created when Christian presents Ana with a lengthy list of sexual acts and asks her to identify which ones she is comfortable with. Readers are aware that Ana doesn't yet know what she likes, but Christian is not aware of this. He assumes she is much more worldly and experienced than she actually is.
Christian's Gift of Tess of the D'Urbervilles (Situational Irony)
Early on in their relationship, Christian buys Ana an expensive gift: a first edition of the Thomas Hardy novel Tess of the D'Urbervilles. The gift is ironic if someone is familiar with the plot of Hardy's novel. In that story, Tess is seduced and eventually raped by a wealthy and powerful man. As a result of that event, a series of tragic events unfold, ending in her death. Ana sees the gift as a romantic gesture, which, on the surface, it is. However, there is also an ironic warning which she refuses to see. The novel should make Ana more aware of the dark potential of pursuing a relationship with Christian, but instead she simply interprets it as a thoughtful gift.
Christian's Initiation into BDSM (Situational Irony)
Ana assumes that because of Christian's strong and domineering personality, he has always been a dominant. Ironically, Christian actually began by acting as a submissive to Mrs. Robinson. This event runs counter to what a reader has been expecting based on the information and based on how he treats Ana. The fact that Christian has been a submissive in the past is ironic given that he finds it almost impossible to understand why Ana is sometimes frightened and overwhelmed. It makes him more likely to assume that she can cope with whatever he gives to her.
Ana's Final Surrender (Situational Irony)
At the end of the novel, Ana asks Christian to show her the worst pain he is capable of inflicting. She hopes that this experience will make her less afraid of him, because she will have seen the worst that could happen. Ironically, the outcome is the exact opposite: Ana ends up horrified and repulsed by the pain Christian inflicts. She thought she wanted to see the full truth of what he is capable of, but this knowledge rips them apart rather than brings them together.
