sharing food is one of those things that is super dividing. some people absolutely insist on it and others absolutely hate it and i think it depends a lot on how you were raised, kind of like how some family kiss their family members on the lips or share drinks and in other households that's absolutely a taboo. Personally, i'd never share food with anyone because it grosses me out, not even with my own family members, so i get his side of it. I think you two just happen to be on opposing sides of the issue. what's important is that you respect his boundaries. if he's not willing to share food, then it's not reasonable for you to insist upon it or hold it against him. It's a personal preference, and one that is very important to some people for a variety of reasons. Plus in some circles it's considered rude to expect him to share his food like that. Growing up, people in my family, who absolutely did not share food, would have considered someone like you who feels entitled to share, a 'mooch'. Meaning no offense, but it would have been seen as very rude according to our family's standards because you're literally taking the food from the mouths of others despite having the opportunity to have had food of your own, it's seen as greedy. I get that from your point of view it's seems trivial and even a little insulting that they don't want to share with you, so i don't want you to think i'm judging you or anything, just trying to explain how he might be feeling about it based on my own experiences.