What does it mean when a girl tells a joke and the person she likes doesn't laugh?

Cultural differences or understanding differences, inappropriate jokes, etc.

1, cultural differences or understanding differences: the humor of jokes will not match the cultural background or understanding ability of the people they like, resulting in their inability to understand or appreciate the humor of jokes.

2, jokes are inappropriate: jokes will involve some sensitive or inappropriate topics, which are inappropriate or uncomfortable for people who like them, and they choose not to laugh.