Different taste in jokes is a great strain on the affections.

Laughing at the same things is a small daily agreement about how the world looks. When it is missing, nothing dramatic happens; you just keep saying something funny into a flat room, or being asked to smile at something you find tiresome. Each time is trivial and costs a little. Over months that adds up to a quiet distance nobody can quite explain.

If someone close to you does not find you funny, it is worth treating as real information. Notice what does make you both laugh and do more of that. And let the rest go unexplained; a joke you have to defend has already stopped being one.