Some person see lying as something that's not too bad, they will even be justifying their lie,that they lied in order not to make the person angry or anything but lying is very bad,infact no judge your actions when you know you lied, expecially in friendship and also in a relationship, some people even think it's their lies that holds up their relationship meanwhile they didn't remember that it only scatter and ruin in cases when one is later identified as a liar.
Who would even be happy you lied to them? Knowing you have been fooled them or you fooled them,knowing someone was happy he or she was able to be fooled? It shatters one's heart ,it breaks one's trust. A saying that "time heals" doesn't always apply to everything, it doesn't technically heals the heart, it just sometimes taught us how to live around the pain,it doesn't always replace what one lost- The trust can never be replaced in 100% again.
Fine, a liar might have a rethink and change ,asking for forgiveness,we surely can forgive but does that mean we actually forget about it? I don't think so because That will take a very long time and constant reoccurring act assurance that most people don't usually get , so I believe when you can rebuild trust when you've decided to see the person in another form ,just like finding beauty in everyone not been perfect but that necessary didn't occur that the betrayal didn't happened, we just get to put it one side.
And sometimes we forgive but didn't give out our heart anymore in order to prevent it from such betrayal again. It's still form of forgiveness but shows it's not the same way it was before. Just like wounds, some will leave an everlasting scar that nothing you use on it will make it unnoticed while some will fade away and you will have to tell people before they get to know .
It's just good and better not to make a lie in the first place, come out clean, if you are going to be accepted ,fine!! And if you are not ,then someone else will at the right time.