Possible cheating in 7 year relationship with no concrete evidence
I have a sinking feeling my partner of 7 years is not faithful to me. I am dating someone who has always been very protective of their privacy which is fine and I conceded for about 4 years. I put all my trust in them and thought the best of them.
We moved in together 4 years ago and things were feeling off so I decided to snoop on his phone. At this time there was no password so I was able to peek into his Instagram messages and saw he was talking to this girl on and off like they were catching up. He exchanged numbers with her and made plans to get dinner together. This person was someone I had never heard of and happened about a year before I moved in when we were living apart. When I confronted him about it I was really calm but he instantly deflected and then only told me that she ended up not coming to town and that he was going to put a lock on his phone. I decided I was in the wrong and apologized for snooping but I still think about that incident years later.
About a week or two later I caught him in the bathroom going through my phone. It was missing from my charger when I woke up and I decided to let him snoop himself because I had nothing in there. When he came out of the bathroom I heard him quickly put my phone back where it was since I figured he heard me get up. I acted casual and then just asked him if he was looking through my phone. He kinda froze up and said that he had exs before who were cheating on him and it started with them snooping. I thought fair was fair but still a little strange considering he didn't want to talk much on the subject.
Now during the past few months I'm getting this dreadful feeling like something is up again. The last 2 months he's been acting weird with his phone. He's been spending a lot of time on it more than usual and walking into another room for a few minutes with it. I'll ask him what he's doing out of curiosity and he'll kinda fumble and give a non answer like "just looking at my phone". He opens it up every time I leave the room even for just a moment to grab something and then puts it away when I come back quickly.
I thought for a minute I might have just been paranoid but he invited his friends over the other weekend and I decided to stay and read in my own room and overheard something. I keep thinking maybe I misheard it with the music they had playing over but I heard them talking about someone I had never heard of before again. His friend asked him if he was talking to this girl on Snapchat still and I heard him say no. Then his other friend asked him something I couldn't quite make out but my partner said no again to which his friend replied "oh ok I would've felt bad if I posted that to Snapchat while you were with (girl's name)."
I thought my brain was making me go crazy but I haven't stopped thinking about it since especially because i didn't know he has snapchat. I don't have any social media at all. I have not checked his phone since last time but I decided to see if he still had a password on his phone all these years. Turns out he now has a id print lock so I couldn't see anything. It was such a gross feeling and I hate that I feel so insecure but I'm terrified that he can lie and deflect so easily. It's even more scary to think that his friends might be covering up for him. The thing that really set me off afterwards is that he said her name while sleeping and that's when I felt like something weird might be going on. I have no way of finding actual concrete proof of his cheating but it still feels so off and I have a feeling I won't ever find out unless someone tells me. I'm really not friends with his friend group at all so I'm out of the loop.