Young couples are more likely to cheat than stay faithful. A 1999 Ball State University study published in the Journal of Social and Personal Relationships found that 68 percent of men and 61 percent of women in relationships kissed someone else, and men tended to go even farther in their cheating behavior. Although it is common to cheat, even on a serious partner, it's unlikely that your girlfriend will take your cheating lightly. It may seem easier to avoid telling her the truth, but the health of your relationship demands that you come clean.

Offer a True Resolution

When you don't allow your girlfriend to react to your behavior by keeping her in the dark about it, you are projecting what you think she will say and do rather than giving your relationship a shot at a real resolution of the issues between you, according to psychotherapist and marriage counselor, Mel Schwartz. The unpredictability of her reaction seems like a good reason to keep quiet, but it is exactly why you should come clean. You can't resolve your cheating on your own and can only do that by working together with your girlfriend.

Honesty Is the Best Policy

The reason what you did counts as cheating is that your activities are secrets you've kept from your girlfriend, according to author Robert Weiss. While coming clean won't absolve you of your behavior, an honest discussion of the expectations you both have of your relationship may give you some much-needed clarity. Maybe your girlfriend thinks that you kissing another girl at a party is no big deal as long as she knows about it. We each have different comfort levels in our relationships, and you owe it to your girlfriend to find out what hers are.

The Truth Will Come Out

Don't add the humiliation of finding out you cheated from someone else to your girlfriend's list of problems. Whether it's through a forgotten e-mail, the person you cheated with or just a sense that something is wrong, there are too many ways for your girlfriend to discover the truth before you work up the nerve to tell her. If you are the one to tell your girlfriend about your cheating, you will have a lot more credibility than if you end up trying to pick up the pieces after she finds out on her own, according to Weiss.

Avoid Relationship Angst

After the revelation of your cheating, you will need to put in a lot of hard work if you want to save your relationship. This means recommitting to your girlfriend, fixing the issues that led you to break her trust in the first place and showing her exactly how much she means to you. If you are unwilling to do these things, this is a good chance to reevaluate whether you and your girlfriend are right for each other and have an open conversation about the future of the relationship.