Yes it's easy and possible to forgive because the bible said that if the partner is willing to forgive the erring partner she or he can do that with love. So if the erring partner is truly repentance and accept the mistake and plead for forgiveness, refrain from doing it again, he can be forgiven. We err (sin) against God severally but when we beg for forgiveness he did that freely, so we too can do the same to others. When we see others as imperfect humans that we do not expect them to be perfect, we will know that they can do mistake at anytime and forgive them inorder for God to forgive our own sin and error too and by so doing nothing will hinder our prayer.

I've seen a case that the husband commit adultery with another woman and have a child as a result of it, the legal wife forgive the husband and take care of that child like her own till the child grow up and become something in life. So it's quite possible to forgive the adultery.
If one cheat he or she should not move on with an open relationship with the person instead they should made it known to others and repent from doing so, plead for forgiveness and pray to God to forgive them also, among all the should not go on practicing it any longer.

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