My eldest is Rose, who is now 22.
Her eldest is John, now 23.
I met my friend Sue when John and Rose were partners in a dancing competition about 12 years ago. The kids got on well. Sue and I became friends too and we still are. The kids were mostly friends through highschool. Sometimes they'd drift as teenagers do. They always got on well at family things like bbqs or nye parties.
Late teens, John developed a crush on Rose and told her he wanted to be more than friends. Rose didn't feel the same. She wasn't unkind about it and hoped they would still be friends. There was an awkward patch while John wanted some space and felt embarrassed. Rose missed him, but was absolutely clear that he was a friend and nothing more.
Then John had a massive strop. It was a big romantic gesture that Rose rejected and John felt frustrated that it didn't work. I get it - he was a hormonal teenager with a broken heart - but Rose was very unimpressed and told him very harshly that her answer was NO, and that him having a strop about it was absolutely not okay, and he needed to pull himself together, accept her first no, and not to bother her until he could act like a decent person.
Then they didn't talk for 2 years.
Happily, time passed and they have become friends again. John admits he was a prat. Rose is happy to be friends again. Water under the bridge.
The thing is, Sue doesn't know any of this. While my dd gave me a play by play account of all of it, John never told his mum any of it. All Sue knows is that they must have fallen out, and for a couple of years, family get togethers were awkward, or the kids made excuses not to come.
Sue asked me at the time if I knew what was going on and I said I didn't. Sue knew damn well I did because she knows dd tells me everything.
Now time has passed, Sue has asked me again to tell her what went on. She knows I know. I think she suspects roughly the right idea. I think she wants reassurance that John didn't do anything terrible (which he didn't).
AIBU not to tell her?
I'm not going to tell her. It's not my thing to tell. It's in the past. It doesn't paint john in a great light.
But I also understand why she wants to know and I do feel a bit mean not telling her.