It's such a human reaction: we're ordered to do something, and our first reaction is to say "No." We say it with all the thoughtfulness of a two-year-old who has just learned to use the word. We say it for the same reason: We don't see how else we can assert ourselves, other than being contrary. So if you tell a two-year-old, "Enjoy yourself!" you might well hear "No!"
What God requires of us -- that is met in loving each other. Think about what God is telling us to do, the lives he is telling us to build. Do we want reconciliation with our families, a large circle of friends, a rich network of fulfilling personal relationships? Do we want to be a positive force in the world and in each others' lives? Do we want to become skilled and accomplished at lifting up other people? Do we want to learn to speak words that people will hold onto like a life-raft when life swamps them? Do we want the pure joy of having a hundred people that are the "friend that is closer than a brother"?
In some ways, God's command is that we live out our deepest desire.
Why exactly do we have such a problem with it?