There are two type of cheating in the world. There is the "accidental" (and I use this word very sarcastically) slip up where someone truly makes a mistake. And there is the ongoing cheating a partner does to another. With the same person, or a series of people. If you had a "slip up", news flash it happens. There is no need to go into the details about why you did that. It was wrong. End of story. However, people make mistakes. Do see your "slip up" as a reason why your relationship has met its doom day. Grow from it. Fix your relationship. However, if you are sleeping with the same person or a variety of different partners while you are with your significant other, do everyone a favor and end your relationship.
If you are cheating on your partner over and over again, chances are that person is not right for you. You can love them, care for them, however if you can't be faithful to your partner then its not the time for you to be in a relationship. Its possible to love someone and still cheat. However, if you really love someone you will have respect towards their feelings. To either stop after the first mistake, or end it before it goes to far.
Its okay to tell yourself, "I am not ready to be in a committed relationship", its also okay to say, "My partner is not making me happy". But it is never okay to think, "hmm, I will just test the waters to see whats out there when I am with my partner", or, "It was just a one time, okay maybe two time thing". If you aren't happy in your relationship, if you are resorting to cheating to make yourself feel complete, its time to end your relationship.
People cheat for a variety of reasons. At the end of the day, its always wrong. However, that does not mean you can't make it right. If you are cheating non-stop on your partner, end it. You would not only spare your partner from further heart break, chances of acquiring a STD, but also you would give yourself the respect you need as well. You deserve to find a relationship where you are happy. You deserve to grow and be part of a relationship when the time is right. Don't rush into a commitment you aren't ready for. Take a step back. Test different waters, when you are single. Its okay to say to yourself, "I love this person, but I am not ready to settle down" or, discover that you need to work on yourself before being with someone else. Its okay to be honest with yourself. However, it is never okay to hurt someone else, to betray their trust. If you are cheating on your partner you are doing that. It does not matter if you apologies and try and make up for it, because it will have scarred them and cause deep pain. Its the ugly reality. However, you can cause less pain by being honest to your partner and yourself.
If you are cheating. Then something is wrong in the relationship. Break up road was your last exit. You are on mistake highway. Take the next exit back to redemption street. You can't take back what you did, but you can always stop yourself from committing the same mistake again.