"Because I'm interested. It's like you've got all these weird barriers set up, like you only want me to have access to this tiny part of you..."
"Yes," she said, crossing her arms. "Barriers. Caution tape. I'm doing you a favor."
"Don't," he said. "I can handle it." (33.51-53)
So here's one reason Eleanor cuts herself off: She wants to protect Park from the nightmarish truth about her family. Eleanor wants to keep Park as separate from her family as possible, and given Richie's appetite for destruction, we understand why.