Matrimony: from Latin matrem (nom. mater) "mother" + -monium, suffix signifying "action, state, condition."
Thus matrimony means "a state or condition from which the Divine Mother can act." Compare with the mystical Hebrew book of Kabbalah, The Zohar:
The verse, "And Isaac brought her into his mother Sarah's tent" [Genesis 24:67], our masters have interpreted to mean that the Divine Presence came into Isaac's house along with Rebecca. According to the secret doctrine, the supernal Mother is together with the male only when the house is in readiness and at the time the male and female are conjoined. At such time blessings are showered forth by the supernal Mother upon them. - Zohar, Genesis 101b
The word matrimony can be analyzed in this way:
In Hebrew, the word נישואים Nishuaim means marriage, and comes from a root that means “to elevate, to rise.” As The Zohar says,
The divine Schekina never separates from one who by his pure life and faithful obedience observed the good law, or covenant. If it be asked, when does the holy Spirit or divine life manifest itself in a man? it is when the union we have just mentioned is effected. It is the true, the divine, marriage when they twain become one flesh. - Zohar, Sex and Marriage
He should make love to his own woman [wife],
Visualising her as my embodiment,
And uniting lotus and vajra [sexual organs] in consummation
I [the Divine Mother] will give him enlightenment.
And the third day there was a marriage in Cana of Galilee; and the [virgin] mother of Jesus was there: And both Jesus was called, and his disciples, to the marriage. - John 2:1
The Zohar, one of the most important books of Kabbalah, repeatedly emphasizes the importance of marriage in religious elevation.
Since all the females in the world are in the secret of the Shechinah [the Divine Feminine], the Shechinah rests upon whomever has a wife, but not upon him who does not. Therefore, Chizkiyahu resolved to be purified before her, and took upon himself to marry a wife. Then he "prayed to Hashem."
The complete explanation of the purpose and fulfillment of marriage can be found in The Perfect Matrimony (1950) by Samael Aun Weor.