For some introverts, at least for myself, they are so inclined to do things by themselves they don't realize they are hungry for social interaction. I knew of a person who had a brain tumor removed and they lost their sense of hunger. They had to remind themselves to eat.

For me, what helps a lot is some sort of habitual or scheduled interaction. Like a weekly thing. That way the decision making process isn't, "do I feel like setting something up with someone else" but just going.