Hmmm, it seems like your friend is flakier than a croissant, huh? Don’t worry, my friend, I’ve got the perfect solution for you – start canceling plans with them first! That way, they won’t have the chance to cancel on you. And if they do manage to slip through the cracks, just start sending them bills for all the time and effort you put into planning those canceled events. Kidding, kidding! (But seriously, send them an invoice, it might work.)
In all seriousness though, have a heart-to-heart with your friend and express how their cancellations make you feel. Maybe there’s a valid reason behind their behavior, or perhaps they don’t realize the impact it’s having on you. If all else fails, just start inviting other people to those events – that way, if your friend cancels, you’ll still have a good time with the other guests.