My Boyfriend Lied? Advice please

So my boyfriend of 4 months just said he's going to be at work tomorrow so can't see me, but I know that he's going to see another girl instead. The thing is I found this out through sent messages so I can't bring this up without him knowing that I know.

The girl he's seeing recently went through a break up and he's been supporting her, which I've been completely fine with, but the fact he's suddenly lied about seeing her makes me second guess... I'm trying to defend him in my head about maybe he's worried I'll be jealous, but I'm still hurt he lied after I've tried to keep so honest..

What do I do?

Confront him, say you went through his phone and know he's been lying to you. Then he has 2 possible reactions: 1) He will constantly point out that you're in the wrong for going through his phone and be pretty angry at you. 2) He will be constantly saying he did nothing, probably get emotional, constantly apologising and eventually explaining, with a believable excuse, why he went to see her (i.e not pretending it didn't happen).

If it's option 1, he's guilty and you should end it there. If it's option 2, I reckon he was genuinely just supporting a friend but thought you'd get jealous if you knew. Although regardless he should've told, I'm sure I'd be hesistant to tell my gf I was going out to genuinely support a female friend in need, so as a guy he's in a tough spot. If he's cheating on you, you'll know, once you confront him about it.

Preferably wait until you're alone with him, not in a public place ofc, to bring it up.

Thank you for your reply. I did want to bring it up, but there's not really been anything noticeably flirty going on, I'm just hurt that he lied. You could argue he was lying to do the right thing, but surely honesty is key?

I know if I bring it up that I know he will be a lot more protective with his messages from now on so wouldn't it be best to try and get over it for now, believing they were good intentions and perhaps bringing it up when I know there is a solid case?

Okay you're clearly really into him, which is cute but you're letting it cloud your judgement a tiny bit. More of a disbelief kind of set of thoughts you've got.

The facts are, he saw a girl AND lied to your face about it. Everything else is just theory, and unless you bring it up all you have is theories. I think the worst possible scenario is that he breakes up with you because he's moved on, and then you finally ask about it and you find out he did cheat on you. That would destroy anyone emotionally, so I wouldn't wish that on you.

If you're willing to give him the benefit of the doubt (and also be able to keep tabs on his phone since he doesn't know you know) then you can, just be careful. One option is, now you mention it, keep checking his phone. Make sure their conversations are strictly supportive and not romantic.

Personally, I still talk to lots of girls, and have a laugh with others too, when I'm in a relationship. I just make it clear to my gf that there's a reason I asked her out and not these other girls. Although I would never even consider lying to my gf's face, especially if it was to cover up seeing another girl oh hell no.

Be careful that's all I'm saying