The act of losing a memory that still exists but is inaccessible to a person because of its disturbing or traumatic nature is know as

Repressed Memory.

Explanation:

Repressed memory is a memory an individual who has passed through a traumatic or disturbing experience has but can't gain access to, because of the traumatic nature of the memory. Repressed memories subconsciously affects the victims of such memories, causing various forms of fear.

on the first day of new student week, amber revealed to her roommate that she is a lesbian. this is an example of self-disclosure.