Spiritual marriage comes from the idea of "love

Love

Love is an emotion of strong affection and personal attachment. In philosophical context, love is a virtue representing all of human kindness, compassion, and affection. Love is central to many religions, as in the Christian phrase, "God is love" or Agape in the Canonical gospels...

 without sex

Sexual intercourse

Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

." It is a practice in which a man and a woman live intimately without engaging in any sexual activities. It has been known throughout many cultures as the bond of a man and a woman for reasons of spiritual and emotional intimacy and connection.
A feature of Catholic spiritual marriage, or Josephite marriage, is that the agreement to abstain from sex should be a free mutual decision, rather than resulting from impotence or the views of one party.

In senses beyond spiritual marriage, chastity

Chastity

Chastity refers to the sexual behavior of a man or woman acceptable to the moral standards and guidelines of a culture, civilization, or religion....

 is a key concept of Church doctrine that demands celibacy

Celibacy

Celibacy is a personal commitment to avoiding sexual relations, in particular a vow from marriage. Typically celibacy involves avoiding all romantic relationships of any kind. An individual may choose celibacy for religious reasons, such as is the case for priests in some religions, for reasons of...

 of priests, monks, nuns and certain other officials in the Church.