Maybe she was treated that way when she's pregnant so she revenges back on you -- a totally innocent person.
Just like one of my former co-workers, she was treated badly in her first job and she's never friendly to me because I was the first junior coworker in the team...
Just like one of my former co-workers, she was treated badly in her first job and she's never friendly to me because I was the first junior coworker in the team...