I am a 23-year-old woman who has been in a relationship with a married couple for 2.5 years. Let's call them Bill and Hillary. When we first started dating there were a lot of rules about who could do what with who, and they were very clear that they would close their marriage again if they felt it was necessary for their relationship. I don't think this was unhealthy—I had rules, too, and of course I could walk away, so while it all felt very weird and unequal, I always knew where I stood. We're a bit more settled, now. Our closer friends know I'm their girlfriend, anything goes in bed, and I moved in with them almost a year ago.

I think Hillary may be cheating on us. (On Bill?) I don't have any evidence, other than that she's been distant for a few months. A friend told me about it. This isn't a friend who knows about me. She works with Hillary and The Guy, and we aren't as open in our workplaces, so she basically framed it as "Should we tell Bill that Hillary is cheating on him?" She supplied a lot of not-quite proof.

I don't know what to do. I'm paranoid now, especially when Hillary is at work until late, which is often. The constant updates from the friend who told me are not helping. Should I talk to Hillary? To Bill? I'm afraid to bring it up at all, because I'm afraid that if this is really happening it might be one of those situations that means closing their marriage. Or if she's not cheating, but I accuse her... I don't think that goes over well in any relationship. And I don't think she would have started dating anyone with Bill's permission but without at least talking to me—I don't think either of them would do that to me—but we never discussed whether I would have a say in something like that. I don't know what's going on here. I am not equipped to handle this. I never even had a boyfriend or girlfriend before them, unless you count a two-week whatever in middle school.

What do I do?

Don't Have A Clever Acronym

My response after the jump...

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You know what you know, DHACA, or at least know what you've been told. And while you don't know whether it's true, you do have your suspicions—all those late nights at work—and you can't 1. pretend not to know/suspect what you know/suspect and 2. keep your mouth shut and risk your sexual health and emotional safety. Because if Hillary's cheating on Bill with The Guy from work—duh—she's also cheating on you with The Guy from work.

And if "anything goes" at home, then Hillary is potentially putting both you and Bill at risk.

So sit Bill and Hillary down together and tell them what you know. And what do you know? Only that someone who works with Hillary is telling you that she's having an affair with someone else at work. Quickly add that there's no evidence, and that this person has no real proof, and that it could be nothing but malicious gossip, but you felt you had no choice but to address it directly.