It would be nice if everyone behaved the way you expected them to. In an ideal world, people would be courteous of others, act responsibly, follow through on promises, do the right thing etc. Unfortunately, we do not live in an ideal world. As a result, we can be let down, disappointed or hurt by the actions (or inaction) of others. It is more painful when we are let down by someone we care about.
In this scenario, you would be right to be experiencing feelings of frustration, anger and hurt. Also, typically, I see people who express those feelings of frustration, anger and hurt. We feel really hurt by someone and we want to get some retribution. Our actions feel justified and actually make us feel better. In the short-term.
What I am advocating here is that
1) You can't control how other people behave
2) you can only control how you choose to respond and behave.
My argument here is that you can choose to behave with integrity. You can make it your personal mandate to act in a way that you hope others would - with honesty, integrity, to say what you mean and to mean what you say. In this way, you can gain comfort that you have made the right choices, and feel comfortable in your actions.
It would probably feel great to fire off that text message to that friend who bailed at the last minute. Or, you can choose to do the hard work - speak up to your friend, find out the reasons and perhaps even express your disappointment. There is a good chance you can move forward and have a more positive friendship. The first option, send an angry text, perhaps not so much. Alternatively, you may make the decision that you won't be the one who bails last minute, or that you give everyone sufficient notice that you are unable to attend. In the end, however, you can't force your friend to not be so flakey.
Engaging your 'wise mind'
We have 3 minds - rational, emotional, and a blending of the two - wise mind. When we respond with our frustration we are acting out of our 'emotional mind'. To act with integrity, we need to engage our wise mind - the blending of the rational and emotional minds. To achieve this take a moment to practice - take a deep breath, down into your belly and notice the deepest point of your breath. That deepest point (eg in the middle of your gut) - this is when you are centered and can make wise mind decisions. Take a moment to feel this centered point and ask yourself - what would happen if I respond out of frustration? Will it make it worse? Am I acting with integrity?
Acting with integrity
Acting with integrity means to be considerate of others, to be honest, truthful, to follow up on what you promised, to be careful with your words (don't say something if you know you won't follow through), to be mindful of the feelings of others and also your own feelings.
You can't control how other people behave, but you can choose to act with integrity.