The correct answer is Paranoia. Chantal likely suffers from: paranoia.
Paranoia is a mental disorder. The symptoms include feelings or thoughts related to persecution and irrational suspicion, which puts the person suffering from paranoia under a state of fear, mistrust or anger. The person might seem normal, performing his/her activities apparently fine, but those feelings isolate him or her from the people around them. It is certainly a disorder that requires medical treatment.