you can expect others to be willing to help - but sometimes you do have to explictly ask for help and not just assume that they know what behaviors they should *stop* in order to *be helpful*

IMO, in the absence of other direction, people tend to act as they would like others to act should they be in the same situation. It may be that the OP's SO doesn't have food temptation issues, so it never occurs to him that it would bother the OP or be unhelpful.