AITA for thinking my husband’s sister is deliberately trying to sabotage my friend’s marriage out of jealousy?
Throwaway account because my husband knows my main.
My (25F) husband (29M) has a sister, “Lisa” (33F). My best friend of 20 years, “Alex” (25M), is married to my soul sister “Sam” (25F). Sam and I are extremely close — we call each other “wife,” have matching rings, and she’s genuinely my person. Sam originally brought Lisa into our friend group because she had no friends.
Last November 2025, at their housewarming party, Lisa got too drunk to drive, so Sam offered her their couch. The next day, Sam had to go visit her grandmother in hospice. She specifically asked Alex if anything would happen with Lisa. He promised nothing would. As soon as Sam left, they had sex on the futon outside to avoid the cameras.
Two weeks later, Sam discovered months of flirty messages where they were bragging about the sex, not using protection, etc. She confronted him that night and locked him out of their bedroom. The next day Sam told Alex he had to tell everyone. Alex waited until Tuesday to tell my husband, then made him sit with that knowledge for a full day before telling me five minutes before I started work on Wednesday. Both Alex and Lisa originally claimed it was just a “one-time drunken mistake.”
A few days later my husband and I took Sam to dinner. On the drive home she showed us the actual messages, revealing months of flirting. In those messages, you could clearly see a couple of times where Alex was trying to shut it down or pull away, and Lisa was the one who pulled him back into it. That’s why her later claim that she was “uncomfortable the whole time” makes no sense to me.
I immediately cut Lisa off.
There’s an 8-year age gap between them. We had seen them flirting but assumed it was just friendly like the rest of the group. My husband had even pulled Lisa aside once and reminded her, “There’s an eight-year difference between you and him.”
Alex started therapy shortly after and has been doing serious work on his trauma, anger issues, and need for validation. We’ve seen real progress.
Here’s where it gets suspicious:
In early January, Alex messaged Lisa once after a confusing New Year’s Eve encounter with Sam, asking for a woman’s perspective. She shut it down. He didn’t message her again until April.
• April 4th: Alex messages Lisa saying he misses their friendship and hopes she’s okay. No reply.
• April 8th: My husband posts a happy group photo of the four of us at the San Diego zoo.
• April 14th: Alex messages Lisa again. Still no reply.
• April 16th: Alex has a therapy session, tells his therapist about the messages, deletes the app, blocks Lisa on everything, and plans to tell Sam after her show.
• April 17th: While we’re at Disneyland celebrating our 7-year anniversary, Lisa messages my husband saying they need to talk.
• April 18th: The next day — and two days before Sam’s first musical performance in five years — Lisa has a two-and-a-half-hour conversation with my husband.
During that conversation, Lisa claimed she had been uncomfortable the entire time, that there were 5 or 6 additional kissing/makeout incidents that were never in any of the messages we saw, and some of her details didn’t match what we already know. She also acted hurt that no one had gotten “her side.”
My husband now mostly believes Lisa. I think the timing is incredibly calculated — she saw that Alex was happy in that group photo while she’s miserable and alone, and she doesn’t think he deserves to be happy after what he did. So she waited for the perfect moment to try and blow up his marriage.
AITA for believing she had malicious intent with when and how she chose to drop all of this?
I want to be clear: I am not defending Alex’s actions in any way. What he did was awful and inexcusable. My main issue is that he has been actively doing therapy, working through his trauma, and has shown real, consistent improvement, while Lisa has done absolutely nothing to better herself. She’s spent the last six months sitting at home feeling sorry for herself and posting vague attention-seeking things on Instagram and Facebook.