When asked "What is hell?" Fyodor Dostoyevsky responded, that hell is "the suffering of being no longer able to love."
I would agree. And put another way, you could say that hell is the absence of love, the inability to either love or be loved, to feel love or to express love. Hatred, cruelty, and what is typically considered evil, are all characterized by the absence of love, and as such, are hellish states of being.
Love is about respect, fondness, compassion, kindness and goodwill. There are many degrees of love. Not just romantic love, but the love between parent and child, between siblings, between platonic friends. Or love may take the form of admiration for someone that you may not know very well. Someone you look up to, that you have great respect for, perhaps a teacher, entertainer, humanitarian, or anyone else that you admire.
But love and admiration may not always be mutual. And that is okay. Real love is about appreciation and respect, not about control or coercion. As Sting says, "If you love someone set them free". There is no love in possession, no love in seeking to contain, to coerce, or to control another against their will.
Love is not just a feeling shared between people, it is a state of mind, a way of thinking, and regarding the world. It may be directed toward people, animals, certain activities, experiences, ideals, or things. For instance, I love pizza. I love watching the sunset. I love the scent of fresh flowers. I love looking at beautiful works of art. That is a form of love too, but it is not mutual. The love of objects or things is of a lower quality than that of the love shared, between living consciously aware beings.
There is a critical difference between obsession and admiration, between infatuation and love. Both love and admiration involves the selfless appreciation and respect for another. Whereas obsession and infatuation differs, in that it is entirely selfish, and somewhat objectifying, by seeking the possession and control of another, irrespective of their feelings or lack of mutual interest.
Selfishness is not self love, it is an obsession with self, without regard for the feelings or well being of others. Love is selfless. Obsession is selfish. The inability to love, respect, and empathize with another, indicates the inability to love oneself. Those who are consumed with hatred, and commit acts of cruelty, are in a state of self inflicted hell, "the suffering of being no longer able to love" either themselves or others.
However you treat others and whatever you put out in the world, whether you act in the spirit of hatred or love, is reflected back at you, and retained by your conscience in the permanent memory of your heart.