Life is complicated, so as they say. But let me tell you something; it only becomes so when you got some great expectations. It's just a tiny thing to change: stop expecting. I know it takes practice to do so. If you can see things as they are without having great expectations, then life will be easier.
Expectations can only leave us frustrated, disappointed, or resentful if we don't get what we expect. Actually, it's only our expectations which makes us judge something (or some people) as good or bad.
When others (your friends, colleagues, lover, family member) disappoint you because you expect something of them and they don't live up to your expectations, it's no longer their fault, but your expectation's.
They're just being who they are. Who were they to know that you're expecting them to your own preferences?
You can still live lightly, by taking small baby steps.
Be aware and especially when you notice yourself having great expectations, take a deep breath and remind yourself, "Good day or bad day, no expectations." Repeat this to yourself till it becomes ingrained in your mind.
See things or people as they are, sans forming your own assumptions or judgments. Why do you think certain people act like the way they do? Get curious and empathize and put yourself in their shoes. Would you act the same way if that happened to you? That saleslady was rude to you maybe because her boss berated her or is down with sickness. Try to be more understanding.
Be more accepting. Don't try to overreact just because something didn't happen as you wanted. You have no control of other people, their lives, or their attitudebut your reaction, you can always control it.
Life can be more beautiful and exciting with some of its cosmic twists and surprises here and there, they may not be always in our favor, but they can always teach us some valuable lessons along the way.