Somebody who invites you ten times after ten no’s is fighting for you. Say yes once in a while.

Ten invitations after ten refusals is not casual. Most people stop at two, so somebody still asking has decided you are worth the small sting of being turned down again, and almost certainly without saying so. You may have had good reasons for every no. The pattern still reads, from their side, as effort going one way.

Say yes to the next one even if it is inconvenient, and go for an hour if an hour is all you have. If you truly cannot, offer a specific alternative instead of a maybe. People who keep asking will take an hour gladly, and they notice who finally came.