Food Anxiety

I have discovered a new area my anxiety effects. That is, I can't take food from people when they are not actively giving permission for me to. You see I have a bf who will frequently leave me at his place to go do whatever. If I get hungry when I'm there I can't eat the food he already has in because I'm too anxious that it is for a purpose or that it's his flat mates food. So I just starve. I don't know why I'm so hung up on food in this way. Just the other day i felt like I was stealing when I took a bit of cheese when i was at my bfs even though I knew for sure it was my bfs and he would have been fine with it. I didn't eat anything else that whole day but that cheese. I didn't realises it is such a massive problem for me until recently. My bf is out more and also eating a totally different diet to me so he no longer has food in that i consider ours. So I can no longer feel safe eating that either. I just starve at his again and again. It's stupid. I sneak breakfast bars from my own house to his so I have something to eat. I don't know how I have been lying to myself so long that it is normal behaviour. I am thinking it's time I talk to my bf and tell him I've got this weird food anxiety when he's not there to give me permission to eat his food. If anyone else has experienced this and has advice or even just relatable story so I know I'm not alone in this specific anxiety I'd be super grateful. Feeling like a complete idiot right now. Just to clarify it's not just at my bfs house, I also can't eat at my sisters, or parents. My bf is just the most obvious example.