Final answer:
Without specific context, it is challenging to pinpoint the exact problem with expectations discussed by Lilian Rubin. It likely involves issues of unrealistic marital expectations or the influence of societal norms on individual behavior and relationships.
Step-by-step explanation:
The specific context around Lilian Rubin's example regarding a couple's expectations was not provided in the reference material, thus making it difficult to answer the student's question with certainty. However, drawing from the common sociological theme that Rubin might discuss, a couple could face problems with expectations if they hold unrealistic views about marriage, possibly anticipating that everything will be perfect ('for better') without considering potential challenges ('for worse') that come with building a life together. This type of issue relates broadly to psychological theories of stress, appraisal, and coping as well as the impact of societal expectations on individual behavior, reflecting the work of researchers like Lazarus and Folkman or the experimental findings on conformity presented by Solomon Asch.