I really need advice — should I bust the door down and ask him right now, or go back to bed and let it slide?

It's a lot and honestly kinda not funny haha. I'm 29, an accountant at a small company in Nakhon Ratchasima. Been with my boyfriend for 3 years since graduation. He's a freelance programmer, works from home a lot so we see each other daily, and trust hasn't really been an issue. Until last night.

Around 11:30pm I was entering data at the dining table with my little polka-dot tea cup that I brewed before 8pm. His phone was on the coaster, then he got up to use the bathroom for like 5–10 minutes and left his phone unlocked with the screen on. I didn't mean to snoop, but the preview popped up: “Miss you so much, want to meet tonight” with a heart-eyes sticker… silence.

My heart dropped. I was so stunned and then I actually picked it up and opened it. Saw a woman’s name I didn’t know, chatting very close — work messages and a ~12-second voice note, a photo of a café pinned to Buriram (he'd done work there before but I didn't know who he went with), and finally “free tonight? I can take you to a movie.” He replied short: “okay.” Just that.

I tried not to jump to conclusions but inside I was on fire, totally lost. My head filled with questions: if it’s a coworker why say “miss you”? And the heart sticker felt so personal. I put the phone back and pretended to keep working, but inside there was a little bomb.

Next morning I checked call history — two missed calls earlier in the month but he never mentioned anyone calling. I asked casually if anyone called last night; he said it was a new client contacting about work. I don’t want to be the jealous type but I asked if there were any personal messages — he said no, just group work chats. His voice sounded unwilling though, or maybe I’m imagining it.

I checked his Facebook and Instagram status, nothing flashy, just work posts. Yesterday he posted a group photo at work and the person standing next to him casts a silhouette that made me start connecting dots. I felt my breath get stuck — even that made my head hurt.

I like clarity. I’m detail-oriented (accountant things), he jokes I can handle all the numbers, but with our relationship I’m a mess circling the same questions. I want solid proof before confronting him, afraid of destroying things for no reason. Also scared of things blowing up.

Little things from before are nagging now: he said he’d work late but then said a friend invited him to drink and he ended up sleeping over at the friend’s place, which he rarely does. Sometimes his phone is on silent, and if I come close he switches modes really fast. Maybe I’m overthinking, or maybe he has a reasonable explanation — I don’t know.

I don’t want to be aggressive or ruin the home vibe, but I can’t take it and I’m asking you all — what should I do? Confront him directly and say I saw the chat, or observe a bit longer? Is there a polite way to get a real answer without making him feel accused without proof?

I’m not trying to expose or hurt anyone, I just want clarity about our relationship. If you were my friend, what would you do? What sentences should I prepare or what should I watch for? Or am I just being paranoid? T_T

Thanks in advance. If anyone’s been through this please share — I really want to read other perspectives, seriously.