AITAH for addressing my boyfriend for opening my juice?

My boyfriend (M 31) and I (F 30) have been together for two years, and he has a habit of thinking whatever is mine is also his. Which usually I have no issue, but it’s gotten to the point where I will have friends who buy me things (drinks, snacks, t-shirts) and he will take them. I won’t even have the opportunity to touch them before he takes them. This week I have been going through a really tough time, and my best friend made me a care package which included juice, snacks, flowers and just really thoughtful stuff that she knows I like. I barely received the package last night and this morning I went to grab the juice and realized he opened it and got some before I had the opportunity to. I’ve addressed him in the past about taking stuff that was a gift for me to work without asking and I don’t know why but today it really got to me. So I reached out to him and asked him if in the future he could at least wait until I opened something before he just decides to help himself (we live together). He says he didn’t think it was a big deal because he didn’t finish it all, and I am frustrated because he doesn’t seem to understand the principle that it wasn’t for him and I would just like the opportunity to be the one to open something I was bought. He said if it’s such a big deal that he just won’t touch any of my things anymore. I don’t want him to think I’m being selfish, because I have no issue sharing? I would just like the opportunity to have something for myself every once in a while. AITAH?