Something’s off with my boyfriend… is it wrong to look through his messages?

Hi everyone, I (25M) have been with my boyfriend (23M) for about 3 years now. Lately, I’ve been feeling like the intensity and connection in our relationship are fading. I know that with time, it’s normal for the “honeymoon phase” to wear off, but in our case, it feels like it’s fading more than it should.

He’s become more irritable than usual, and I often feel like I annoy him just by being myself. Our sex life has also declined noticeably, and it’s starting to make me feel unwanted. On top of that, I’ve noticed he’s on his phone a lot, chatting with lots of different people. That’s made me start to wonder… is he being unfaithful?

I know his phone password, and I’ve been tempted to check his conversations. I haven’t done it yet, but I keep asking myself: should I? I don’t want to violate his privacy, but at the same time, I’m starting to feel like something might be going on behind my back.

Has anyone been through something similar? How did you deal with it? Is looking through his messages a terrible idea, or is it justified if I truly suspect something