Depression, anxiety, poor health are what come to my mind. My friend thinks people who do this do it for a power trip. I love my friend but she consistently does things to power trip people which is why she assumes other people do things for power tripping reasons. I have no real idea why the people who do this to you do it, I don't know them. When I don't show up for something it's usually a health or mental health reason so that's where my mind goes. There are soooo many possible reasons but what matters most is how it effects you and the boundaries you need to set for your own well being. I've discovered it's best not to mind read people's intentions because the conclusions you draw often have more to do with yourself than the other person.....but sometimes we just "know" a person is manipulative and if this is how you view these friends, it's best for all parties involved to part ways as it's unlikely it will change or lead to anything positive.