fate I don't think Belle thought she was ill.
Her only diagnosis came from some who came to her house and electro scanned her body. He then gave her what she claimed was oral chemotherapy.
That person doesn't exist not to does any form or portable scanner. I think her story is entirely made up. I also believe her bf and business partner knew as well.
She was given the all clear several after finally undergoing actual medical tests. But failed to admit it or come forward with that detail.
People lie about being sick all the time. And it's for a range of reasons. Attention, gain money (like Belle), time off sick, take advantage of people's kindness, exaggeration, they think they are actually ill etc.
I think it's very common. Tbh I couldn't do it. I would feel like I was wishing bad luck on myself.
My mum, dbro and sil do this it to some degree. Dbro and his wife make it worse. She had a cough for a while. I made her go to the doctors an was sent for a scan. The scan showed a shadow, but they couldn't give a verdict. She was told to come back a week later for another scan. We were all worried. Dbro googled it and told her it was likely cancer. That was it she told her sisters it was cancer. She didn't say it was diagnosed, but that she knew it was and she would die. I know my mum has mental health issues, so does dbro. I was so angry at him doing this. Mum then became obsessed with googling it.
Dad was worried sick, dbro and sil were throwing themselves round about what would happen and how to arrange care for her.
I looked at what she was googling and she was looking up cancer. Not shadows. In the end I googled one thing like 'what does a shadow on a lung mean' in front of everyone and the information that came up was quite reassuring. Lots of people who had shadows that disappeared by their next scan.
Dbro and sil are always at the doctors for themselves or their kids. They averaged more than one appointment per week last year.
I very sternly handed them both their asses. Had a stern word with mum about listening to them and calmed my dad down.
I was so angry with dbro as he knows her mental health history. He didn't help at all. He enjoyed the drama and didn't go to work for a week to support her 
The next week the shadow was gone and didn't come back. It was likely phlegm or something similar. 2 years later she is fine.