Rules. Or demands or expectations. They're all the same thing, really.
What is a rule?
[Let's disregard practical boundaries; they're just external mechanisms for negotiating the world effectively. We're looking at internal rules: the reason for all unhappiness.]
It is a condition I place on my happiness. It says: "I can only be happy if X happens / does not happen." I then, consciously or unconsciously, monitor compliance with the condition.
Rules feel like defences against suffering, but they actually create what they seek to defend against.
For example, if my rule is 'don't hurt my friend', because to do so would cause me suffering, the rule creates the suffering, because either the rule is broken, in which case I have resentment, or the rule might be broken, in which case I have fear. Rules that can't be broken are never generated as rules in the first place. The whole point of a rule is a condition on what is uncertain. Every rule, therefore, necessarily generates the unhappiness it seeks to protect against.
The only difference between rules lies in the following:
"What would you like, Sir? Resentment or fear?"
"I would like resentment, please."
"In that case, pick a rule that is frequently or inevitably broken. Then you're always resentful it has been broken."
"I don't like the sound of that. What about fear?"
"Then pick a rule that is infrequently or not necessarily broken. Then, you're always frightened it might be broken."
The real subconscious purpose of rules is actually to create resentment and fear, both of which project out the internal sense of wrongness and locate it elsewhere.
Do I want to be happy? Yes!
Drop the rules then. You can be happy straight away, right now.
The only remaining block to happiness is then the internal sense of wrongness, which we must allow to dissolve, as an aberrant illusion. Where is the wrongness? It is nowhere: it is fabricated. Drop it. That is all.