I'll give an example.
Me and my Dad don't have the best relationship. He had a bunch of affairs while we were growing up, and my Mum was very unhappy as a result. He also had very little interest in us as kids, always preferring to be off doing one of his hobbies.
To be fair to him, he has tried to improve the relationship with his kids over the past 10 years or so, but I still keep him at arms length, we'll generally go for a few pints together every fortnight or so.
The problem is, he really does want to go for that pint, but he also doesn't want to commit to doing it on a specific day, just in case he gets a better offer. So we'll have a conversation, one of us will say "Shall we go for a pint next week?" I'll say "Yep, how about Tuesday", and he'll say "I'll give you a ring on the weekend, and we'll decide what day then" Half the time he won't then phone on the weekend, but will still be expecting us to go for a pint on Tuesday.
Now, I've tried to talk to him about this. I've explained that it's hurtful, I've explained that it brings up issues from our past, and that its also frankly annoying to have to keep an evening free when there's no guarantee that we'll actually be going out. He makes all the right noises, and then does exactly the same thing two weeks later.
So I'm left with petty. I won't go out of my way to organise something else on Tuesday, but if someone else suggests it, then I'll say yes, because after all, I don't have any firm plans. Or if he doesn't actually confirm that we're going out, I'll wait until he's on the bus into town, and when he texts to say he's on the way in, I'll say "Oh, you didn't confirm so I thought we weren't going, I'll head in now" and he'll have to sit in the pub for an hour.
When he whinges, I tell him every single time that it's his own fault that he refuses to confirm plans, but he doesn't learn because he's too worried that he'll miss out on something better.