Guy's Behavior

Guys, is he cheating or am I overthinking?

I have been dating a guy for over a year. He may also be a covert narcisist. Lately I have been seeing things that felt "off" but never mentioned them to him to avoid seeming like a toxic girlfriend. I have also been cheated on in the past so I'm unsure if I'm overly sensitive or if I'm recognizing signs.

He used to sell cell phones but hasn't in a while. A couple of weeks back I saw an old phone in the truck. He acted like he was considering using it again. Now just 2 days ago I noticed the cell phone repair kit out, but no phones to repair. He insisted on going to his brothers house and left at almost 9pm, insisted I didn't go, and only stayed about 40 mins. Came back in a VERY good mood and wanting to "have a late night/fun" etc. I declined because it was almost 11 and we had an early and long day the next morning. He's also started playing this zombie game, he's never been into gaming and it consumes a lot of his time. I've seen the game and there's not much to it but he often looks like he's texting. When I watch him play he kind of just clicks around, but its always on a hot girl character. Before he moved back in with me, he purchased a computer for his room at his brothers house - his computer is at my house and I don't use it, and have offered for him to take it back often. Why does he need another monitor if he never uses the one he already has? If you open safari on his phone it is always opening to a new tab, never the last searched page. We haven't been intimate in 3 weeks (he's 27) and we recently did a "factory reset" so except for the above mentioned things, "emotionally" we have been better than ever. Without planning to, I told him I felt like he could be cheating and described a few of the things above. The way he looked me straight in the eyes without blinking to say "I'm not" was almost TOO emotionless, like when you KNOW that people analyze your blinking or shifty lying eyes so you overcompensate... There is SO much more. Please help.

Guys, is he cheating or am I overthinking?
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