An offer of company should include permission to change their mind.

An invitation that cannot be declined later stops being an offer and becomes a small debt. People agree on a good day and then find themselves obliged on a bad one, so they hesitate to say yes at all. A stated way out is what makes the yes free. It usually produces more real company rather than less.

When you next offer to come along, say plainly that they can call it off with no explanation owed. Then mean it when they do.