Everyone can make a mistake, even you, so if the shoe was on the other foot, you would like to be given some leniency, or at least have someone list to what you have to say, wouldn't you? When you hold a grudge, the only person it really affects, or let's say mostly affects, is yourself.. You don't want to carry around a big knot of hurt and hate in your heart, not now and not ever. So, forgiveness is necessary on all levels. 1.> To free yourself from feelings that can disable you from moving forward or stop you from loving again. 2.> To give the other person on some level a chance to redeem themselves to be able to start building trust again. Forget, now this is not so easy, because even if you do manage to open your heart and forgive for all of the above reasons, you may not forget so easily. It's a matter of trust and time, and if over time trust can be reinstated, then forgetting will eventually come. Life and the relationship we have are precious, think carefully before throwing them away, without first looking at all angels and outcomes. If there is anyone who you need to forgive.. Think about it and live a happy life! :)