I feel you have to sympathise with this situation, which is a combination of two (or more) individuals with psychological problems.
No-one 'allows' themselves to get into a state like this - this individual has serious psychological problems obviously coupled with phsyical problems connected to digestion and fat conversion.
Add to that a partner who has a different set of psychological problems that prevent her from seeing the on-going situation, much less doing something about it.
There are large sections of society who have no real control over their lives. They allow things to simply 'happen' to them, because they lack the mental capaicty to take any sort of charge of their circumstances.
Hopefully this man seriously intends to change, for the sake of his family and his potenail life - he is obvilously close to death.
Because western society has ain in-built superiority / loathing atrtitude to obesity, it is easy to condemn this man as simply greedy and / or stupid, but it is plain his problems are far more complex and deep-seatied than that.