I believe people hold grudges because they are really hurt or struggling with forgiveness because that is one thing many many people do not know how to do it’s just natural to the human
A grudge may arise from many human emotions. Jealously, sadness, anger...etc. When we get over one, it allows us to heal and when we don't, it can turn worse. For example, your really close friend forgot your birthday and now you have a grudge against them because you are hurt, angry and sad. They were your friend! but you feel betrayed and thus, you hold a grudge against them and once solved, you'll either get closer to your friend or have a damaged freindship.
