The worst part is the unknown. The pain of being alone, the loneliness, is familiar. You've dealt with that. You understand it. But loving someone, risking everything, is unknown. There's no way to know how bad it's going to be. You barely survive the pain of being alone, so how can you deal with anything worse? So you don't bother to try.
There are only two emotions: love and fear. All positive emotions come from love, all negative emotions from fear. From love flows happiness, contentment, peace, and joy. From fear comes anger, hate, anxiety and guilt. It's true that there are only two primary emotions, love and fear. But it's more accurate to say that there is only love or fear, for we cannot feel these two emotions together, at exactly the same time. They're opposites. If we're in fear, we are not in a place of love. When we're in a place of love, we cannot be in a place of fear.
We discovered that peace at any price is no peace at all...that life at any price has no value whatever; that life is nothing without the privileges, the prides, the rights, the joys that make it worth living and also worth giving...and that there is something more hideous, more atrocious than war or than death; and that is to live in fear.
He had been driven hither by the impulse of that Remorse which dogged him everywhere, and whose own sister and closely linked companion was that Cowardice which invariably drew him back, with her tremulous gripe, just when the other impulse had hurried him to the verge of a disclosure.
To know a species, look at its fears. To know yourself, look at your fears. Fear in itself is not important, but fear stands there and points you in the direction of things that are important. Don't be afraid of your fears, they're not there to scare you; they're there to let you know that something is worth it.