Because I'm bloody well sick and tired of buying peanut butter, only to find when I actually fancy eating some that he's eaten it all for his breakfast and not bothered to replace it.
I really want jam and peanut butter on crumpets for breakfast this morning, but can't, and actually I bet he's eaten the last two crumpets as well - yet another item that only I remember to buy but never get to eat.
Had enough.