Man Asks If He's Wrong To Leave The Peanut Butter In The Kitchen After He Stuck His Penis In it

Sharing space is quite tricky and often requires us to draw some boundaries. A young man recently faced an issue that has apparently divided the home he lives in, a space that he shares with four other guys. He took to Reddit to share the issue, anonymously, so he could get some clarity on the issue with the help of Redditors. He started off by saying he requires assistance for something that has apparently divided the house into two groups. I'm looking for some assistance determining whether I am the asshole in this situation that has divided our house into two groups.

He then gives the readers a small background into his life. I (20M) am a college student living with four other guys my age. It's our second year living together, and last year we had an issue with people eating food that isn't theirs, so now we have a strict "label your stuff and only eat things with your name on it" policy." That's basically how most people deal with their space, especially when it comes to food. If it has your name on it, no one else is supposed to take it. 

My girlfriend and I like to get a bit frisky in the bedroom, and a few nights ago I dipped my penis in peanut butter and she licked it off. Yes, I understand that it is slightly bizarre, but that's how we roll. The controversy is that since we have a mouse problem I did not want to leave the peanut butter in my bedroom, so afterwards I closed it and returned it to my kitchen cupboard. Note that it had a huge "PeanutButterDilemma" label on it, so it was clear that it belonged to me." He only used what was labeled his and what he does with his stuff is his business, isn't it?

However, it seems like he did not think of a situation where someone else would use his stuff. One of my roommates tells me yesterday "oh by the way, I had some of your peanut butter". He sees my visibly shocked reaction and asks what's up, so ultimately I come clean about the whole deal. He's furious and says "why the fuck would you put it back in the kitchen". I remind him of the mouse situation and our policy not to have other people's labeled foods. I appreciate the fact that he was honest about it. He could have easily hidden it from his roommate. 

This is the first time all year that somebody has had my labeled food and informed me after the fact. He said it was just some peanut butter on his bread, it's not like he was taking full chicken breasts from me. My house is split 3:2 on who is in the wrong, and it's spilling over into other aspects of our living situation. We need to get over this pronto so I am asking... AITA?
INFO: We have sort of divvied up cupboards, so it was kept in "my" space. It wasn't in a communal cupboard. 

It's quite unsanitary that the man left the peanut butter back in the kitchen, but also unwanted of his roommate to use something that wasn't his, to begin with. Basically, everyone is wrong here, and that was the final conclusion that Redditors came to, too.