The accused protagonist
For our protagonist, we have Harriet, an academic young woman who was recently implicated in a murder. That is to say that our good guy in this book is a potential murderer. This means that she will have a hard time being perceived in a positive light. She is clearly the protagonist in the novel, but even in her community, she is received with mixed review. Perhaps this irony is a symbolic reference to the controversy and disdain that feminists face.
The poisoned waters
The problem of the novel seems to be that one person is spreading dissension in the school. Although positivity and optimism are strangely weak in the novel, the pessimism and hatred of a single person poses a serious problem for the school. The irony is similar to poisoned waters (poison is a common symbol in the novel, by the way); if a person dumps fresh water into fresh water, the effect is mild, but if someone adds poison to fresh water, the water becomes unsafe. This irony points to negativity and paranoia.
Public perception and the protagonist
Although the protagonist is obviously someone with a difficult, tedious relationship to public perception, having been thought of as a literal murderer, she is asked to help her institution restore their public perception. Her journey is ironically to give to others what she wants mostly for herself. She is like a martyr of guilt, because her life is covered in accusations of guilt, but she must help her organization become less guilty in the public eye.
Wilson, the self-traitor
Annie Wilson is a strange person to be the issue. For one thing, much of the graffiti and persecution she uses is anti-feminist, and she is a female. This is even more ironic because she takes a stance of moral superiority, arguing that women who try and become educated are harming themselves and the community at large—but that's literally what she's doing the whole time. She harms herself by weakening her opinion of women to such a hateful position, and she harms her community actively, on purpose. Her hypocrisy is quite ironic.
The strangely pleasant ending
Of all the endings this novel could have had, the marriage of Harriet and Wimsy is ironic. This doesn't seem like a romance at all, until they reveal that they've been falling in love the whole time. This adds another layer of meaning onto the text. Wimsy helps Harriet to defend her feminism, so he becomes an eligible spouse to her, because they have already cooperated politically. Wimsy has no misgivings about who Harriet is, and Harriet doesn't have to worry about Wimsy suddenly taking a traditional stance about gender and gender roles.
