You should never lie to your partner. Honesty is so important. If you lie to them about an event that happened and they found out, how does your partner know whether they can trust you again? Even if you hid the event and didn't lie about it, if your partner did find out, they probably still would have trust issues from then on.
If your partner can't accept that you made a mistake, then the love might not all be there. You should be able to confide in your partner knowing that they won't ever be mad at you. And same with them back to you. Honesty is very important for a relationship to work.
It may be a cliche but truth does hurt...But if you tend to hide it..You deprive the other party to choose. Hiding the truth means deciding for the other party to believe what really is isn't.
When something bad happens, one should confess! Its natural for the other party to feel bad but then again it is just fair for him/her to know what is going on and choose how to deal with it.
Everything we do has its consequences, and betrayal is no exemption.
If you were weak enough to betray, surely you gain strength through admission.
I believe in honesty. If you are having issues with your partner, have the guts to tell them about it. If not, no one says you have to continue the relationship! Betraying, is the most selfish lie one could tell. I rather confess before i get caught cheating... How awful will you feel then?
Not every case is the same and it also depends on why you are confessing. If you are confessing just to feel liberated, then shut up, carry your guilt and hope God does not condemn you to eternal hell. Of course, try to be a better partner and don't screw it anymore.
If you are confessing just because you have some misplaced notions about honesty, then just think about how would that confession would make the partner feel. Think about the pain, the anguish, depression and other things that come with it. Once it's out there, it cannot get it back in.
If you think your partner can handle it, then go ahead; but IF and only IF you think it can literally destroy her/his life and you love her/him, then just keep quite, no need to make his/her life miserable.
As I said, it depends on the situation and the kind of people we're dealing with. There are a lot of different circumstances and variables but I think I made my point.
Nobody's perfect and people make mistakes. I personally believe there's no point in telling someone that you cheated on them once if it's never going to happen again. It's your mistake and only you should have to live with it; telling them will only hurt them and most likely lead to the end of the relationship, so nobody wins. However, if you find yourself cheating on a regular basis or the one night stand turns into an affair that is an entirely different matter. Having a moment of madness and sleeping with someone on impulse is one thing, but to knowingly and continually go behind someone's back and lie to their face is utterly unforgivable. If you do that to someone, you clearly have no real respect or love for them.