Yeah. Cora did have friends when she was 10. She lost those friendships and became socially awkward and I guess you could say felt betrayed of the idea of friends so she keeps herself close enough to get by in duels but the idea of friends is new and terrifying because of her accident and what the outcome had been. 

Hanging around Duel Monster Spirits, great! But actual people, nope. 

Might check it out. Sneak a peek at it.