This is idealism. Compassion/Lovingkindness meditation is very helpful for idealism. Opening to our own and others' ignorance. To understand how difficult it is to deal with our ignorance at times so that we soften our attitude towards ourselves. Instead of "I should already be perfect, I should already be able to let go of this or let go of that," it becomes, "Ah, the power of ignorance is strong. I'll try to deal with these hindrances as they arise." So reflection on Dukkha and the power of ignorance helps to soften our attitude towards ourselves and also helps to soften our attitude towards others.
"You should not..." Sounds like you probably have idealism towards yourself, too. Compassion/Lovingkindness and understanding how we cannot control others helps us see that this type of attitude leaves us very vulnerable to unhappiness. How can we control, even our own mind, at times. Reflecting on how difficult it is to control our own mind and actions, can help us to soften our attitude towards others. So I would probably guess that this person also has this attitude, this idealism towards themselves, as well. So more Compassion/Lovingkindness meditation is helpful.
Strengthening the mindfulness practice also helps us to come to realize how difficult it is sometimes to deal with our own mind states. It is not so easy to deal with the greed, the hatred and the ignorance. And if your happiness is dependent on whether other people act as you would like, do what you want, then you are leaving yourself very vulnerable to frustration.
Strengthening Compassion for yourself is very, very helpful here, so you are not seeking happiness dependent on external things such as other people to love you, to speak the way you like them to speak, to do what you want so that your happiness will be fulfilled rather than make you suffer. Understanding the third characteristic, that there are many things beyond our power to control, helps to lessen the idea that we can control other people.
The second of the Four Noble Truths helps us to understand that Dukkha arises from our own ignorance. That is the 2nd Noble Truth. Dukkha arises from ignorance, craving and unwise views. So if we are always seeking not to suffer by trying to make other people not do things, or do things, then we are bound to end up suffering because we are not following the truth. Reminding ourselves about the Four Noble Truths can help us refocus our attention more on how we are reacting to what other people are doing, rather than believing if somehow we could control them, then we would be happy. Ultimately, Dukkha arises from ourselves, not from others. So reflection on the Four Noble Truths can help. Reflection on the 3rd characteristic, not me, not mine, helps, too. Lessening our attitude towards "should and should not."
People are ignorant. There is a lot of ignorance in this world. Most people don't have any right view about where suffering really comes from. Many people are not taught how to deal with life, with their mind, so strengthening Compassion can help us let go of our idea that everybody should know what they should do.