Relief is a response when fear has disappeared.
The derivative emotions of fear are relief, uneasiness, and awe.
Relief occurs when fear or uneasiness, which is an expectation of fear, disappears. Relief is an emotion which branches out from fear's disappearance. For example, an airplane which we are riding shakes violently and after the shaking subsides we feel relieved. Relief occurs when one is released from danger or anxiety.
When people feel relief they heave a sigh of relief and smile. After this they let go of their wariness and physically rest. The tension in the body has disappeared and the body is going to physically recuperate.