Mental health issue. It's dialogues.

My Bhabhi his very short tempered. She cannot be happy for more than 4-5 days. She keeps looking for small topics to create an issue out of them. When angry she can cross all limits and say anything. She keeps thinking all the time and doesn't trust anyone. She has this habit of doubting everyone, specially my brother (her husband). She doesn't like to sit with anyone for too long. After every week, she takes up any random topic and then create a big fight out of it. She loves living in closed environment. She keeps her door closed all the time and stays inside it. She doesn't like talking to people. Her habit of not keeping happy is becoming a concern for us as her 2 kids are also suffering from the same. Please help if this an issue of mental disorder because she watches serials and keep ranting it's dialogues.