Relationships are complicated, and when there is cheating, lying, and deception involved, they get even worse.

What would you do if your best friend cheated on a guy who you were also friends with, but she told you not to tell him?

That is the situation that the girl in this story was put in, so she kept her secret. When the guy finally found out, however, he felt that he was betrayed by not only his ex, but also his friend.

Honestly, he isn’t wrong. Everyone treated him poorly here. Read through the full story and see what you think should have happened.

AITAH for not telling my best friend’s boyfriend that she cheated on him?

I’ve had a best friend, “Lena,” for over a decade. We met when we were young and have basically grown up together.

Having close friends is a real blessing.

She’s one of those people I’ve always thought would be in my life regardless of what happened.

So, this story happens when we’re all in uni. To be clear me and Lena went to different unis at this time.

All of these friends overlap, which can be great.

A while ago, Lena started dating “Mark.” He was a fun guy, seemed good to her and coincidentally went to my uni. He and I slowly became friends, although obviously I was much closer to Lena.

Mark was also close friends with someone Lena had previously been involved with, “Ryan.” Their past relationship was complicated and never really had a clean label, but everyone knew there had been something between them.

What a mess.

Ryan was coincidentally friends with Mark before Lena was ever in the picture. It was actually Ryan who introduced Mark to Lena.

Lena is polyamorous. Ryan is also lowkey poly. Mark had always considered himself monogamous, but because he cared about her, he agreed to try a relationship with her anyway.

It did nooooooooottttt go smoothly.

You can never force this type of thing to work.

They spent months arguing about boundaries, jealousy, whether certain people were okay to be involved with (Lena and Ryan hooked up once as part of the open relationship and mark was ok with it till he suddenly wasn’t and made a whole thing of confronting Ryan), and whether Mark was actually comfortable with the arrangement or just trying to make it work because he loved her.

There were several times where they nearly broke up, then reconciled. She would always be mad that he accepted her polyamory in the moment then would backtrack a week later.

If they were apart, she was free to do what she wanted.

At one point, they decided to take some time apart. During that period, Lena and Ryan hooked up again.

I didn’t think much of it at the time because, as far as I understood, Lena and Mark were genuinely on a break. Whether that technically counted as cheating was never really clear to me, and I wasn’t interested in policing their relationship.

Lena seems like a terrible girlfriend.

Eventually, Lena and Mark got back together. Things continued to be messy. They fought constantly and there were trust issues on both sides. Eventually, they had another major argument and ended the relationship for good.

I thought that was the end of it. Then, sometime afterward, Lena told me something I didn’t know before.

She admitted that she and Ryan had hooked up shortly before the final breakup, when she and Mark were technically still together.

Her loyalties are with her friend, though covering for a cheater is never a good thing.

She hadn’t told Mark. She told me because I was her best friend and apparently she felt guilty and needed someone to talk to. She specifically asked me not to tell anyone.
I didn’t.

Her guilt slowly faded as the breakup got worse, he called her horrible names and treated her like an object. But this is where I probably screwed up.

He needs to get over her and move on.

Mark and I were also friends, although not nearly as close as Lena and I were. After the breakup, he was obviously devastated. I talked to him, listened to him vent, and tried to help him get through it.

There were times when he asked me whether I thought there was any chance he and Lena would get back together. I told him I thought he needed to let the relationship go and stop worrying about Lena and Ryan.

She was trying to do the right thing.

I never directly lied to him. But I also didn’t tell him what I knew. Part of me genuinely believed that telling him would just make an already horrible breakup infinitely worse.

They were already done. There wasn’t anything he could do about what happened, and I didn’t want to be the person who dropped a bomb on him just because I felt like he was entitled to every detail.

Lana isn’t a great friend either.

The other part of me was admittedly selfish. Lena has been my best friend for more than ten years. She told me something in confidence and made it very clear that if I told Mark, she would consider that a huge betrayal.

And honestly, I was scared of losing her. I also didn’t think it was my place to decide whether her confession should become public knowledge. She had already made a mistake and the relationship was over. I thought maybe some things are better left between the people who were actually involved.

Mark is not in a healthy headspace; that’s for sure.

But then Mark eventually became suspicious. That suspicion wasn’t based on anything concrete, he had just been driving himself nuts with the thing between Lena and Ryan for months even during the relationship and it just came to a head.

To be clear, mark has not had the most stable life or headspace for a lot of his adult life and is very erratic. He confronted Ryan about whether something had happened between him and Lena.

This is becoming quite the mess.

Ryan apparently panicked and admitted that they had been together. But did not specify that it was during their relationship.  His basis of confrontation hinged on screenshots he had from my boyfriend of some alleged conversation between him and I.

But I didn’t tell my boyfriend what had happened, no conversation had happened. Ryan comes home and tells me and Lena about the confrontation (he is really good friends with the both of us to this day and he and Lana still hook up sometimes.)

All of these people sound exhausting.

Mark then confronted Lena, and blocked her. Now it was my turn apparently. He calls me and tells me he has evidence, tells me I’m a bad person for not telling him.

But I got upset too because I kept telling him not to bring my boyfriend into this matter and drag him into the mud. I asked him to show me the screenshots and this man folded so fast and immediately admitted that there were no actual screenshots.

He isn’t wrong, really.

But this is also what he said to me:

He said that while he was sitting there questioning what went wrong with his relationship, I knew that one of the people he trusted had betrayed him and deliberately chose not to tell him.

He also pointed out that I had been there comforting him while withholding something I knew was directly relevant to the breakup.

Mark has a good reason for feeling betrayed by his friend.

That part really got to me. I told him I never pretended Lena was innocent, and I never encouraged him to get back together with her. If anything, I repeatedly told him to move on.

He said that wasn’t the point. According to him, I took away his ability to make an informed decision about his own relationships because I decided what information he was allowed to have.

This is why gossip, lying, and deception are such a bad idea.

And honestly… I don’t know if he’s wrong. Lena, on the other hand, thinks he’s being unfair. She says I was her best friend first, that she told me something privately, and that I had no obligation to expose her because their relationship was already over.

She herself no longer felt guilty because of all that he put her through during their relationship. Some of my other friends are split.

Hiding infidelity is almost never the right thing to do.

One person told me, “You didn’t cheat on him, but you helped someone hide cheating.”

Another said, “If Lena told you she was assaulted or had some other deeply personal secret, would you think Mark automatically had a right to know? You can’t just assume every secret belongs to the other person.”

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Another friend thinks I should have told Lena that I couldn’t keep something like that from Mark and given her the opportunity to tell him herself. After his mental break she was also willing to tell him, but it would mean Ryan losing some of his other friends connected to mark.

Her intentions don’t matter much, but her actions do.

That honestly sounds like the most reasonable answer in hindsight, but at the time I didn’t think about it that way.

There’s also the fact that Ryan is the one who eventually admitted it. If he had kept his mouth shut, Mark might never have been convinced it was true since his screenshots were fake.

So, now I’m questioning whether I was actually protecting my friend’s privacy or just protecting myself from having to choose between two friendships.

She was put in a difficult spot; that’s for sure.

I didn’t lie. I didn’t invent an alibi for Lena. I didn’t tell Mark that she hadn’t cheated.

I simply stayed silent when I knew the truth. But I also knew that Mark was hurting, and I knew something he didn’t.

Honestly, she was put in an impossible position where she had to betray someone.

So, was I wrong for keeping my best friend’s secret and not telling her boyfriend that she cheated on him?

And if I was wrong, was I wrong for keeping the secret at all, or was I wrong specifically for continuing to comfort Mark and tell him to move on while knowing something he didn’t?

AITA?

Lana seems awful, but this girl is bad, too. She is the one who put her in a situation where she had to lie (directly or by omission) to a friend.

Read on to see what the people in the comments have to say about this horrible situation.

If you have to lie, you are likely the bad guy in a story.

Her best friend is worse, but she is pretty bad.

Yup, it is this simple.

If you enjoyed this story, check out this post about a man who got fed up with all of the cars parking illegally on his vacation land, so he had them all towed.

This is the exact question she should have asked herself, but she didn’t.

She would hate it if someone did this to her, though.

This whole group of friends seems horribly exhausting. They all behaved poorly, especially she and her best friend.