I think the discomfort comes from knowing that internally - you have an emotional connection to the issue.
The key to getting it out on the table is to disconnect from that emotional attachment.
Jst the facts please - just the facts.
The facts of this case is that you have blocked time out of your schedule for this person. You have given up other opportunities to do other things you may be interested in.
To have him pull the plug on you at the last minute is equivalent to him taking the last piece of pizza - and throwing it away !
Simply inconsiderate and unfair.
And you're NOT going to take it any more