How do I get my boyfriend to be more open about sharing food?

My boyfriend is really territorial about his food.

He doesn't like anyone to try his meal when we go out, not even me, his girlfriend of two years. He doesn't even like to share his fries; he says if someone wants fries, to get their own.

I've asked him time and time about being more open about this, and pointed out he can try my food too, but he's not interested. He said he wants to eat what he ordered, he's been looking forward to it, and isn't interested.

His only "compromise" is to get a bowl of fries to share if I want fries but don't order any, or he said he's happy to order me two meals and pay for them if I Want to try something else.

WHY CAN'T HE JUST F-CKING SHARE? It's really pissing me off, I even talked to his mother and she said he's always been that way - his food is HIS.
Updates
+1 y
We are Australian not American
He is not autistic

Sharing food is an expression of love and intimacy and is part of a relationship

Some of you must have shitty relationships if you’re on his side
How do I get my boyfriend to be more open about sharing food?
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