Telling the boyfriend will probably upset your daughter and would also be an action that goes outside of your household instead of dealing with her choices within your household.

Since it is your daughter who is cheating, it may be best to pump up your parenting skills and power by talking with her privately at home when her boyfriend isn't around and teaching her the difference between good behavior and questionable behavior. It's also a good time to teach her about being responsible and making sure her boyfriend knows the truth about what is going on so that he can then make a decision about whether he wants to stay with her and be in an open relationship where they can both date other people or if he wants to stop dating her and date someone who will only be his exclusive girlfriend.

It is very important for her to understand these things, especially if she and her boyfriend are sexually active. It isn't fair to him to not know what he is dealing with but telling him crosses some boundaries that parents should not do.

If you want him to know and your daughter refuses to tell him,

another option would be to talk to his parents and they can tell him.

No... you shouldn't. Meddling in your daughters relationship is like lighting a firework and waiting for it to blow up in your face.

If you do feel obliged to do something then you can talk to your daughter about it. Helping her is the way to go. But I suspect you're going to have to allow her to make her own mistakes, and learn from the inevitable fall out.

Absolutely not. Talk to your daughter, since she is the one who is doing something you neither approve of, or taught her to believe. If you don’t attack the source, the problem doesn’t go away.

I wouldn't tell her boyfriend, but I would tell her. I don't know how old she is, but it may be time to remind her how deeply unethical most people feel this is - regardless of how she feels about it. Some people even refuse to date others who've cheated in a previous relationship. Ever.

I wouldn't tell him and I'm not sure approaching her with it directly is the best way to go about it right from the get go. Our kids (at any age) don't learn much if we don't let them. Personally, I would bring up a similar situation to her and ask her opinion about it. This gives her the chance to look at her own actions from the perspective of an outsider as she compares what she does to the scenario you offer. This also gives her the chance to be independent and make her own decisions.

Right or wrong, it's not our place to make our choices for our kids. It's our place to help them to learn how to make their own good choices. Besides, getting involved by telling him is only going to cause her to lose trust in you and put you in the middle of their relationship. in my experience, the messenger often gets more blame placed on them than the offender. Be neither and simply be a parent.

Not at all.

If ANYTHING you should talk to your daughter about cheating. Explain that beyond it being "wrong" it can get you into a lot of trouble.

I would actually recommend that she dumb her boyfriend, but not tell him, keep life simple.

You just overheard it. Talk to her and find out the truth. This is the best time to let her know cheating is not good.As a parent, you can give good advice and show her the good ways to break up with her boyfriend, if she doesn't like him. Does she has any other issues regarding the cheating?
It is always good to talk to our kids before we say anything to their friends. Being a parent, you have your child's best interests at heart. Give your child more opportunities to trust you.

What your daughter is doing, is not right, if she no longer loves her boyfriend, she should tell him, let him go, let him find love in other place.

Talk to your daughter, ask her what are her feeling for her boyfriend, ask her to put herself in her boyfriend shoes.

And after that put yourself in that guy shoes, does he deserves this?

Heck no! Pull that daughter aside, sit her down, and let her know how disappointed you are in her!

Have a nice long talk about cheating, and how if she had any courage, she would've broken up with the boyfriend before wandering. About how cheating cheapens her own value, by giving it away to another guy who doesn't have to treat her nicely or worship her. About how lying breeds lying. About class, integrity, and self-respect.

If you do it right, she will go and resolve the situation with the boyfriend on her own.

Absolutely not. Hopefully she'll eventually mature enough to do the right thing and tell him herself. If I were you, I wouldn't even say anything to your daughter about it no matter how much you want to. She'd probably be so upset/embarrassed and the last thing you want is your daughter telling you she hates you and to leave her alone. Even though she wouldn't mean the "hate", it'll still feel hurtful to you. I know how my mom felt when I said mean things to her.. I still say mean things to her sometimes and I always regret it and apologize right away.

yes,tell him

No, assuming that your daughter is old enough to be dating then , it is not your place to talk to your daughter's boyfriend. You should talk to your daughter and she should solve her own situation. You should guide her in realizing the dishonesty of what she has done; but this should be done in a quiet and understanding way to help her mature into a more responsible adult.

If anything you should encourage her (Tacitly, without letting her that you know) and help her keep it hidden from her boyfriend. Most marriages are doomed anyway, especially with young cheaters. These people are never satisfied. Moreover , these memories would be the only ones she can hold on to, when she is 35, fat and single because her husband of 2 years left her.
Let her be and make sure you dont tell her a thing.