Does Plato assume that it is better to know the truth and be unhappy than to be happy but ignorant Would this assumption be correct?

Yes, in Plato's philosophy, it is better to know the truth and be unhappy than to be happy but ignorant. This is because he believes that knowledge and wisdom lead to a more fulfilling and virtuous life, even if it comes with challenges or sadness. He values intellectual and moral growth over mere pleasure or ignorance.