It's so easy to set the record straight and STILL not be an ass.

I'm an embellisher with a bad memory, so details in my own stories sometimes don't match up. I confuse left and right, don't care about exact numbers, stuff like that. When friends call me out about it jokingly, I just say "haha yeah I don't remember exactly but YOU GET THE GIST"

That's all you have to say: "my wife isn't a fan of details but you get the gist" or "haha we do have different narration styles". Telling a story is never about the facts, it's a bout the effect. Would you like to hear a play-by-play of how I went to the grocery store, with timestamps? No. Telling a story is entertaining people.

You are a team, and you're not a team player. By "correcting" her, you're making her the outsider you put your friends in an awkward position too by making everyone pick sides in a "he's lying/she's lying" middle school fight. If she says something really outrageous, just say "well it was more 10 than 5 kilos" to her, with a smile. That way you're BOTH telling the story. Don't belittle her about things that only matter to you and make everyone awkward over nothing. Everyone uses metaphors, but you're the one being an ass about human communication.

What are your friends reactions when you retell a story? From what I've gathered ("our lives aren't that interesting") she feels her life is interesting and she can make it interesting to others. If you suck the joy/interest out of a story and make things awkward by being a bore about something that is not boring that's on you. You're making things awkward and belittling jour partner while she's telling. You're making things awkward afterwards because you can't tell a story. Ask jour friends if they find her narration style egregious, and if they don't take a look at yourself.