I don’t even know how to start. Honestly, last night around 00:20 I accidentally saw something and got a bit heated, but also...kind of confused.

I’m in Chiang Mai, a high school teacher at a small school near home, early thirties. Been with my girlfriend almost three years. Things fit in a lot of ways — not flashy, just chill. We’ve met each other’s families. She works in an office in town. Our worlds are a little separate but it’s fine.

Last night she said she was going to a send-off party for a coworker who’s leaving, said she’d be back around 10pm. I said okay, then I stayed at school finishing some paperwork and watched a series, had a paper coffee cup next to me.

Sometime after midnight I was mindlessly scrolling my phone and accidentally tapped it. Her LINE preview popped up for a group with a polite name like “Project Team” but the message that showed was just one line: “Found it, let’s walk over and check together, I’ll call.” And there was a teasing laughing sticker. I didn’t mean to snoop, but I ended up staring for like 10–15 minutes, honestly.

I looked back through the chat kinda unintentionally (sorry, I stared way too long) and saw she’s been talking more with one person — close, casual, inviting each other to eat after work, sending photos of food back and forth like best friends. But there were messages that made me uncomfortable, like “I really want to see you today” and she replied “I want to see you too.” Like, what is this.

Also that person knows weirdly specific details about her life — stuff she’s told only me, knows the day we hang out, even knows she prefers strong black coffee. Like he’s been following her news or something. I checked stories and saw a photo at a coffee shop near the Koong Ton Kwen bend (I go there sometimes) and she commented under the post like they’re really close, chemistry on point.

I started overthinking. I’m a teacher — trust is huge for me. I don’t want to be possessive or control anyone, but when you put it all together it gets thick, like a fog and I can’t see clearly.

The next morning I asked lightly, “Did you come back late last night?” She answered flatly, “Oh, just hung out with friends a bit, came back after midnight.” I nodded, forced a smile, didn’t ask more, but my heart was pounding. I wanted to ask straight out but I was afraid of ruining the mood. What if she gets mad? Or what if she’s lying and it gets worse?

Another thing: her coworkers when they see me often avoid me or don’t make eye contact. Some stop talking when I’m around, but when she turns to them they laugh big. I feel left out in this weird way, like I’m not myself there at all.

I get that relationships need personal space, friends, life outside work, but I’m scared that if it crosses a line I’ll be hurt. Or am I just stupid to put up with this hoping there’s nothing? I’m tired of holding these questions in and letting them become fog. Now I really can’t see straight.

Should I ask directly, “Is there someone else between us?” Or ask softer like, “What’s your friend like?” I’m scared the answer will hurt the person I love or break the trust. I teach kids about relationships but I’m completely lost with my own.

Or should I keep watching and not say anything? Or find a time to talk seriously during the day when no one’s around? I’d really appreciate anyone sharing experiences or tips on how to bring this up without wrecking things. Please help T_T