Denial is a feature, not a bug, in the human psyche … it’s necessary to preserve homeostasis of identity or worldview. It is also employed to conserve energy.
Denial arises in response to two forces …
the information / or evidence being presented
- will cause emotions that the person believes (unconsciously) that they are not capable of handling, or that they would be unsafe to feel
- will rob the person of a source of nourishment … for example, breaking up with an unfaithful partner would create a lot of stress and energy consumption if forced to slip back into dating / single life
The diagnosis of your partner is not particularly relevant … the determining factor will be WHAT YOU BELIEVE YOU CAN FACE OR HANDLE