Why don’t people just forgive? That is a very good question. If forgiveness is easier and more beneficial, why isn’t it more popular? The sad reality is that there is short-term, relationally destructive power in refusing to forgive. Holding onto the other's wrongs gives us the upper hand in our relationship. We keep a record of wrongs because we are not motivated by what honors God and is best for others but by what is expedient for ourselves.
The article lists five temporary "benefits" from not forgiving, but then shows the long term bad consequences nad the better way of forgiveness. So much more at the link above.