Try this
- Write the no so the plan is no longer ambiguous, then add a warm statement only if it is true.
- Keep an alternative invitation separate and specific. Avoid implying that persistence may change an answer you have already made.
A worked example
“I’d love to see you another time, but I’m not joining this outing.”
An invented example to adapt, not a real exchange or a script you have to follow.
Before you leave it here
Do not soften the no so much that it sounds like a tentative yes.