Guy's Behavior

Why is he hiding me and our convos from her?

I love this guy, friends to lovers. on and off for a long time. only guy I let hit it. we can’t seem to leave each other alone. However, about 3 months ago we were together then he leaves me for another girl. I was heartbroken, he dropped the whole we should stay friends line and that he loved me but thinks we should see other people cuz we are still young. He got in a relationship with that girl, then she started talking crap about me, he kinda brushed it off so I was quiet about it from then on. then she started lying on my name, saying I was talking about her. He got mad at me. So I told him off. Then now we are friends again and we have had an on and off again friendship (because of her always lying to him about me.) I think she sees me as a threat. I talked to her to clear the air (which in my opinion I didn’t need to do considering I got fucked over) then I find out that she’s still going around talking to people about me. I think she is intimidated by the bond me and the bond I made with this guy. I stayed “friends” with him because that’s what he said he wanted. These past few months I think he realized he fucked up (and admitted it) but he also has come onto me in these months. We still unintentionally flirt with each other but I’m still upset with him. Recently, we have had a lot of deep intellectual conversations over text. He sent me photos of his parents happy together, (shouldn’t he be sending them to his girlfriend). he was texting me on Snapchat then all of a sudden tells me to text him on a different app, then unadded me. I know he feels bad about what he did apologizes for it constantly. If him and I are “just friends” again, why would he have something to hide? It seems like he is holding back his feelings. But what is their to hide if he’s with the girl he fucked me over with and we are “just friends”? He’s the one that wanted this, fucked up our relationship for it.
Why is he hiding me and our convos from her?
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