Or single people who have been so starved for affection that they don't know how to receive it. People can be emotionally blind, crippled, handicapped because their heart has grown cold. And this is not okay. It is not how we are meant to live. When Jesus met people his heart was warm, he responded with compassion.
Compassion means to feel or suffer with.
Jesus understood in his heart what others were thinking and feeling. This kind of blindness is very common today, perhaps because we are so materialistic. Or perhaps we don't believe in Satan because we are afraid of the power, the subtly of evil. This is the blindness that refuses to see the profound struggle and cost of God's victory over Satan and all his minions. Ignatius of Loyola had a way of training his followers for discipleship, it was called the Spiritual Exercises and they are still used today to form lay and ordained men and women for service.