We've been together since 2021, and throughout the first 2 years of out relationship I had nothing but the utmost trust in her. She was always brutally honest with me, and I noticed that she was very comfortable with her phone around me; she had no problems checking texts or just being on it with me there, and even would tell me her pass code (say if she was driving). It really helped me to feel secure and it was one of the things I really appreciated.
We hit a rough patch last year and broke up for a few months. It wasn't clear if we'd get back together but after a while it was clear both of us wanted to and about a month ago we did. She did sleep with someone else during the breakup.
Her behaviour around her phone is different now. She's hesitant to open her phone around me and has changed her pass code. I have a feeling there's something she's hiding but I'm not sure if it's something going on now or something from the break she doesn't want me to know about.
This past weekend she went out to a bar with a friend. She updated me throughout the night, and called me around 3am to pick her up.
The next day, I fell asleep in the afternoon and woke up at 2am to an empty house, no texts from her, and her location was turned off. She had work the next day, so my first thought was that she was cheating, so I used her laptop to access her emails and get into her snapchat account. I turned her location back on, and later would find out she was at a friend of her's, why she had her location off is beyond me, but its what i found in her snaps that I want to talk about.
The first thing I noticed was that she had been snapping a guy whose name I didn't recognize, and had a 7 day streak with him. She keeps streaks with a bunch of friends, so that didn't stand out, but when I read the messages from the previous night, my stomach sank. She was flirting, and at one point he mentioned her tattoo, to which she replied "you'll see it irl soon enough."
When I called her out, she swore up and down that she didnt remember, that it was the tequila talking, and that it was the first and only time she'd said anything like that to another guy since we got back together. If that's true, I'm inclined to forgive it, but said I needed proof that it was a one-time thing. I asked if she would request the conversation history from snapchat and let me read the rest, but she's refusing, claiming first that she didn't want me to see her venting to her girlfriends about me, and when I said I wouldn't read anything but that convo, she said it was "just too invasive."
I know that's bullshit, and I know what's probably going on here, but I know if I walk away now without knowing what's going on here, whether she was simply humoring the dude for attention or if it's gotten physical, it's going to eat at me forever. How do I either convince her to agree to this, or otherwise get to the bottom of this?