Impact bias, a type of affective forecasting, (hyperlink?) is a a type of emotional durability bias. It is essentially a human prediction about how long an emotional reaction will last.
Impact bias, a cognitive bias, is the tendency to overestimate the intensity or the duration of future emotions and states of feeling. This overestimation can occur for both positive and negative feeling states. Most of us can remember times as children believing that "If I get that for my birthday I will never want anything ever again and it will be my favorite thing forever!" This emotional reaction may last for awhile, but then eventually fades when boredom sets in or something else is desired.
Another example would be experiencing a breakup and feeling as if you'll never be happy with anyone else again. But give it some time, some healing and eventually the negative feelings will go away and you can picture yourself being with someone else and being just as happy as you were before.