Psyche is the word that originates from the Greek psykhé and is used to describe the soul or spirit.
It's also a word related to psychology, and it started to be used with the connotation of mind or ego by contemporary psychologists to avoid links with religion and spirituality.
human psyche
According to Carl Jung, the human psyche consists of psychic processes that can be conscious or unconscious.
Sigmund Freud, the father of psychoanalysis, defended the notion that the human psyche is divided into three parts: id (unconscious part), ego (conscious part) and superego.
Psyche and Eros
Psyche and Eros are two figures from Greek mythology, which tells the famous love story between the two.
Psyche was a woman with exemplary beauty, so much so that she aroused the envy of Aphrodite (mother of Eros). After suffering a lot because of the goddess of love (Aphrodite), Eros made her immortal, with the help of Zeus.
Eros is the word that refers to a type of love, a romantic love. Thus, it is possible to conclude that the love between Eros and Psyche is a story of the alliance between love (Eros) and the soul (Psyche).