Suppose you are in a situation where you know someone who has lost somebody, a close friend or a family member. If we only focus on impermanence and expect this person to be over their loss shortly after the event, we are not opening to their humanness in how difficult it is to lose close loved ones. In this situation, there is equanimity but not enough compassion. Equanimity towards life, but not enough opening to how difficult it is to be a human being who experiences loss. After a certain length of time, maybe a year, perhaps this person develops some equanimity towards their loss, understanding that everyone dies.
Equanimity is "hard" when there is not enough compassion, usually there is a lot of reflection on the characteristics of existence, on impermanence and the impersonal nature of things. But not enough understanding and opening to how difficult it is for people to experience Dukkha. So if a person is having difficulty, there may be the thought, "Oh, it is their problem," which denies the opportunity to feel with this person,s difficulty and perhaps help in someway.
One of the most beautiful stories in the scriptures is the mustard seed story. This story is about a woman whose son died after being bitten by a snake. The woman ran all around the village searching for a doctor to heal her child and she was sent to see the Buddha. The Buddha could have said to her, "Well, everybody dies", in order to get her to accept it, but he didn't do that. When this woman came to him and lay the child before him and said, "My child is sick, I need some medicine to heal my child", the Buddha said, "I will heal your affliction". The woman's name was Kisagotami and the Buddha was going to help her, but he said, "I need a mustard seed from any house where no one has died". Kisagotami was very happy on hearing this as mustard seed is a very common ingredient in Indian curry and she did not understand the significance or importance of her task.
She raced off to the village to find this mustard seed so that the Buddha could help her child who was dead. She simply wouldn't accept that he was dead. So she went to every house in the village, asking people "Do you have a mustard seed, the Buddha needs some mustard seed to heal my child". Of course they looked at the child and realized that the child was dead. But, well, the Buddha needs it so they gave her the mustard seed, but when Kisagotami asked them, "Has anyone died in this house?" Of course they said, "Yes, I am sorry". They lived in extended families then, "my grandfather died last week," etc., etc. Every house in the village she went to the same answer, "Oh, I am sorry, my son has died." Or "Oh, I am sorry my mother has died," etc.
By the end of the day she had been to every house in the village and she realized for herself the universality of death. And through this simple compassionate skillful means of a mustard seed, the Buddha helped her to open to the universality of death, a very compassionate opening to this woman's plight. Not showing just equanimity. He had equanimity but he opened to this woman's plight and knew a skillful way to help Kisagotami come to this understanding herself.
So if we expect others to know the truth of existence, we may have equanimity and understand it is their Kamma, however there may not be identification with that person's suffering, feeling compassion and trying to find an appropriate way to express our compassion so that they can come to their own understanding. Sometimes if someone is unable to open to other's suffering, getting over whelmed by them, people may exit into what they think is equanimity, but it is often indifference, not wishing to spend the time to listen to that person and identify with them before giving what they feel are solutions. So there is not enough compassion in those situations, sometimes the solutions may be helpful and if they do, it they could be able to end their Dukkha, but often times people just want to be heard and understand that you are feeling with them as a human being before taking your suggestions.
Learning the true balance between compassion and equanimity can be quite helpful. One way to develop a good balance of equanimity and compassion is to do a type of meditation where we reflect about a person's Dukkha, trying to feel compassion for them and instead of the Lovingkindness phrase do develop more equanimity by saying the phrase "they are the owners of their own Kamma". This reflection is especially helpful if we have seen we are getting overwhelmed by others Dukkha and caring too much. Reflecting in this way helps us to understand that it is not our responsibility to end their Dukkha.