My partner's “stalking” on social media makes me uncomfortable. Am I overreacting?

I’ve 36/M been with my partner 28/F for 2 years, and I’ve noticed that she has a habit of diving really deep into people’s social media profiles. By that, I mean she’ll look at comments, descriptions, and then figure out who the commenters are—basically profiling them. I always hoped I’d be an exception to that level of stalking, but it turns out I was wrong.

Throughout our relationship, we’ve been open about our pasts: we’ve shared stories about exes, how those relationships started, how they ended, and so on. I’ve never tried to hide anything from her. I also suspected she’d done similar “investigations” on my exes in the past, but I had never directly caught her doing it.

Recently, she created a Facebook account. Initially, she said it was to join some expat groups in Canada (we’re looking at moving there), and since I already had a Facebook account that I use mainly for photo dumps to update family, we became friends on the platform. One night, we slept separately due to back pain (we wanted to see if a softer couch would help), and the following morning she told me she’d had trouble sleeping and ended up scrolling through over ten years of my Facebook history.

I thought it was weird—unnecessarily invasive—even if I understand that being Facebook friends technically gives her access to my profile. But what really bothered me is that she screenshotted various photos of female friends from years ago (most of them were acquaintances) and, even more concerning, she also saved photos of two exes. These exes are from 8 to 10+ years back, in another country. She knows what they look like because I’ve been open about them, and I’ve never hidden any details if she wanted to know.

She admitted she sent at least one of those screenshots to a friend of hers so they could talk about my ex. I’m guessing she might’ve sent more. In one case, she even found that ex’s current social media profiles and looked through everything. She told me, “I think we would’ve gotten along—her posts seem funny,” which made it obvious how much she’d read through.

When I confronted her, she said she doesn’t see a problem with any of this. She insists she’s always done it, and that her friends think it’s fine, too. But I can’t help feeling like it’s a huge invasion of my privacy—especially since she’s screenshotting and sharing photos of people who aren’t in my life anymore. Am I overreacting by feeling that this crosses a line? I totally get that Facebook is public to friends, but this kind of intense “investigation” just seems excessive. I’d appreciate any advice on how to handle this.

AITAH for confronting my partner and expressing that this behavior is unhealthy, damaging, and wrong

TL;DR: My partner “stalked” 10+ years of my Facebook, saved screenshots of old friends and exes, and shared them with her own friend. She thinks it’s no big deal, but I feel uneasy and invaded. Am I overreacting, or is this level of social media sleuthing a red flag?