When a person cheats on their partner, they betray the trust that has been given to them. A partner who loves them may be willing to attempt to salvage the relationship. It is a difficult process, and the cheater must be prepared to have their entire life brought into question. If they really want the relationship to continue, their only choice is to be completely transparent. Total honesty about where they are, what they are doing and talking about their true feelings will be required to earn the trust they carelessly tossed away.
There are few people willing to go to great lengths to continue a relationship with a partner that has cheated, and the cheater will often feel it is not worth the hassle to continue the relationship either. If they get caught lying or even hedging the truth just once, they have almost no chance of keeping their relationship alive. A second chance is very rare, and those who manage to regain trust have found a partner who is truly worth their faithfulness.