Which character is Holden infatuated with and upset to learn is Stradlater's date?

Holden is infatuated with Jane Gallagher and becomes upset when he learns that she is Stradlater’s date. Jane is a former neighbor and friend whom Holden remembers fondly, especially for the emotional connection they developed during the summer.

Holden’s concern is not simply ordinary jealousy. He worries about Stradlater’s reputation for casual sexual behavior and feels protective of Jane, while also being unable to express his own feelings to her directly. His repeated questions about whether Stradlater had sex with Jane intensify the conflict between the roommates.

Jane is important even though she appears mainly through Holden’s memories rather than as an active character. He recalls playing checkers with her and noticing that she kept her kings in the back row, a small detail that shows how carefully he observes and remembers her.

Sunny, the young prostitute Holden meets in New York, and Sally Hayes, another girl he dates, are separate characters. Phoebe Caulfield is Holden’s younger sister. None of them is Stradlater’s date on this occasion.