The term paradox is defined as a literary device in which an author lays side by side two ideas or concepts that seem contradictory but hold some "hidden and/or unexpected truth" ("Paradox," Literary Devices). Not all paradoxes are rhetorical, meaning pertaining to language use; some paradoxes are situational. A situational paradox is one in which "characters find themselves in difficult to reconcile circumstances" ("Paradox").
Katherine Mansfield's title "Bliss" is paradoxical because the protagonist Bertha feels bliss on a very ordinary day when nothing out of the ordinary has happened to change her situation. Her situation consists of having a husband she merely likes but is not passionate about, having a baby she barely spends time with, having a comfortable home, and having lots of friends, yet none of these things have ever before given her a feeling of bliss, only a feeling of contentment. The one thing that is different is she has met yet another beautiful friend, named Pearl, whom she had "fallen in love with," just as she always fell in love with women she thought were beautiful and mysterious. It is possible that her feelings of jealousy of and admiration for her friend have given her hope for developing further feelings for her husband, and she is interpreting this hope as a feeling of bliss. Sadly, since she can neither fully identify what her feeling of bliss is nor express it because she feels she must suppress it, by the end of the story, she no longer has her feeling of bliss, which further underscores the paradox created by the title, a paradox that presents truth since suppression of feelings certainly does lead to a loss of feelings.
Since Bertha is unable to identify exactly why she feels bliss, she projects her feeling of bliss onto multiple objects and people. For instance, she projects her feelings onto the centerpiece of a bowel of fruit she has just created, onto her child, onto her friend Pearl, and finally onto her husband, whom she says she "[f]or the first time in her life, ... desired." She even wonders if her feeling of bliss was stimulated by her growing desires for her husband. However, she suppresses her feeling of bliss by preventing herself from telling her husband about her feelings, keeping herself from laughing, and by talking as much as possible throughout the evening. Her difficulties in identifying her reasons for her feeling of bliss and of expressing her feeling because her feeling is not genuine show us that she is a character in a situation that is difficult to reconcile, which shows us she is in a paradoxical situation.
Her lack of genuine feeling of bliss is further revealed when, by the end of the story, she draws the conclusion her husband is having an affair with Pearl, a conclusion that shatters her feeling of bliss and leaves with her with the same ordinary feelings she has had every day. The contradiction between the title of the story and the story's outcome further develops the paradox, and it is a contradiction that makes perfect sense to the reader since a person will lose a feeling of bliss when the feeling is either not genuine or is suppressed.
The tension between the title and the theme of "Bliss" is more apparent than actual; the paradox comes from how Mansfield handles the complexity so gracefully. The bliss Bertha experiences is also quite literally ecstasy: ec-stasis. Bertha is lifted out of her norm, her place, and her habits by the feeling. This is what opens her to the possibility of new and potentially transformative desire for her husband. However, when one rises out of one's normal position, one sees and experiences new things, and that's what happens when she sees her husband with Pearl. To put it more simply, bliss destroys contentment.