What is the theme in Bliss by Katherine Mansfield?

The themes of marriage and adultery are central to "Bliss." Bertha believes (or makes herself believe) she has a fulfilling, complete marriage. Although she characterizes her husband as a good pal, she still contends they are as much in love as they ever were.

The climactic event of the story - Bertha's realization of Harry's affair with Pearl - proves that her husband does not share his wife's contentment. As Harry's affair demonstrates, he is not happy with the lack of passion in their marriage. Harry's actions reveal his duplicitous nature: not only has Harry been hiding the affair from his wife, he also pretends to dislike Pearl in order to cover it up. The risk that Harry takes in kissing Pearl in his own home, as well as his method of hiding his true feelings, indicate the likelihood that he and Pearl share a very strong connection.