In that context it's called denial.

denial -n
A psychological process by which painful truths are not admitted into an individual's consciousness


In my view "delusion" would be an appropriate word to describe your example.


I think Bogdan's suggestion of escapism fits the bill

noun

The tendency to escape from daily reality or routine by indulging in daydreaming, fantasy, or entertainment.

so that person would be an escapist

noun
Someone who wants to escape; especially from reality