The Church Fathers speak of this interpretation in antiquity. I'm not sure of the source but it has been a widely held concept in Catholicism. The idea is not a novel one, St. John Damascene (676 – 754)
For the Anointer and the Anointed were one and the same, anointing in the capacity of God Himself as man. Must there not therefore be a Mother of God who bore God incarnate? Assuredly she who played the part of the Creator's servant and mother is in all strictness and truth in reality God's Mother and Lady and Queen over all created things. But just as He who was conceived kept her who conceived still virgin, in like manner also He who was born preserved her virginity intact, only passing through her and keeping her closed. [Ezekiel 44:2] The conception, indeed, was through the sense of hearing, but the birth through the usual path by which children come, although some tell tales of His birth through the side of the Mother of God. For it was not impossible for Him to have come by this gate, without injuring her seal in anyway.
The ever-virgin One thus remains even after the birth still virgin, having never at any time up till death consorted with a man. For although it is written, And knew her not till she had brought forth her first-born Son [Matthew 1:25], yet note that he who is first-begotten is first-born even if he is only-begotten. For the word "first-born" means that he was born first but does not at all suggest the birth of others. And the word "till" signifies the limit of the appointed time but does not exclude the time thereafter. [John of Damascus, An Exposition of the Orthodox Faith]
And then there was John Cassian (360 - 435):
Jerome, the Teacher of the Catholics, whose writings shine like divine lamps throughout the whole world, says in his book to Eustochium: "The Son of God for our salvation was made the Son of man. He waits ten months in the womb to be born: and He, in whose hand the world is held, is contained in a narrow manger." Again in his commentary on Isaiah: "For the Lord of hosts, who is the King of glory, Himself descended into the Virgin's womb, and entered in and went forth from the East Gate which is ever shut." [Ezekiel 44:2] Of whom Gabriel says to the Virgin: "The Holy Ghost shall come upon you, and the power of the Most High shall overshadow you. Wherefore that holy thing which shall be born of you shall be called the Son of God." And in Proverbs: "Wisdom has built herself a house." Compare this if you please with your doctrine or rather your blasphemy, in which you assert that God is the Creator of the months, and was not an offspring of months. For lo, Jerome, a man of the greatest knowledge and also of the most pure and approved doctrine testifies almost in the very words in which you deny that the Son of God was an offspring of months, that He was an offspring of months. For he says that He waits ten months in the womb to be born. But perhaps the authority of this man seems a mere nothing to you. You may take it that every one says the same and in the same words, for whoever does not deny that the Son of God is the offspring of the Virgin, admits that He is the offspring of months. [John Cassian, On the Incarnation]
Source. Translated by C.S. Gibson. From Nicene and Post-Nicene Fathers, Second Series, Vol. 11. Edited by Philip Schaff and Henry Wace. (Buffalo, NY: Christian Literature Publishing Co., 1894.) Revised and edited for New Advent by Kevin Knight. <CHURCH FATHERS: On the Incarnation, Book VII (John Cassian)>.
Saint Thomas Aquinas gives a complete explanation as to "Whether Christ's Mother remained a virgin after His birth" at
this site
I would say stand in the company of saintly teachers.
JoeT