lose touch with reality
To no longer have a firm or clear understanding of real life; to lose one's ability for clear, rational thought. A possessive pronoun can be used between "lose" and "reality." The poor guy sort of lost touch with reality after the death of his children. I feel like I'm losing my touch with reality lately—I think I might need to see a psychiatrist.
lose touch with reality
to began to think unrealistically; to become unrealistic. I am so overworked that I am losing touch with reality. The psychotic criminal had lost touch with reality.