Why do I snoop?

We dont have passcodes because we trust each other, so when he told me to reply to his work friend I did. Except I saw messages above that, and they were quite flirty.

Now dont get me wrong I'm not opposed to flirty banter between friends if your partner has said its okay and stuff but he was being flirty and she was kind of trying to brush him off and it almost seemed like he wasnt taking the hint?

Idk if I'm being crazy, or have any right to get mad because of the snooping, but does anybody else think its something I should talk about with him? There were a few messages from him with stuff like "Oh yeah, in your bed 😉" when she was asking what he was up to later and stuff. Idk.

Am I crazy? Is it me being pregnant? I havent been as insecure as I have since the start of this pregnancy so maybe its that.