Extrovert finds, likes and adopts an introvert as a friend... two years later things start getting quieter and the introvert thinks its their own fault, so they make things awkward for a minute before they further blame themselves for ruining the friendship and decide to distance themselves for the "benefit" of the extrovert.
Introverts need some sort of reaffirming interaction, otherwise they'll just make it harder on themselves, there's a reason they need you to find and adopt them.