The issue Here seems to be lacking Scripture, or cultural norms ( by law) among Jews.
The mohar (bride price), the Ketubah (later) was a contract (covenant), before conjugal relations. This is what was joining together as the wife of the covenant. Therefore betrothal joined them together, and she was not a mere concubine wife, divorcement bills were necessary due to the covenant (ketubah). Mary remained the wife of covenant (ketubah) in their joining as husband and wife.
Protestant ideas or Catholic matter not. What does scripture say? IMO, we see this same distaste for scripture with Abraham and Sarah. Neither was faithless or mistakes made in giving Hagar for a CONCUBINE. No matter how deplorable one may consider such practice. Are we to sit in Judgment of the law?
Mary was the wife of the Ketubah, making her distinctly a wife as an helpmeet in the covenant.
Abraham also took Keturah after Sarah's death. She also was a concubine. Sarah was the only wife of covenant no matter how many concubines Abraham might take.
Jesus didn't come to us keeping secular law, or posited law, but God's law. However even secular and posited law were kept by Mary and Joseph. Mary’s betrothal with Joseph was for the maintenance of Mary and here child; Mary need a man for her to raise the Christ Child. We can see this in the vow of Mary’s chastity, “because I know not man”. This required Joseph to decide whether or not to expose Mary as a harlot or permit her to fulfill her vow. Being a “just man” Joseph needed only a dream like visitation to convince him not to put aside Mary to be stoned to death at the gate of the villiage. A characteristic of a just man is one of selflessness and charity.
11 If the wife in the house of her husband, hath bound herself by vow and by oath,
12 If her husband hear, and hold his peace, and doth not disallow the promise, she shall accomplish whatsoever she had promised.
13 But if forthwith he gainsay it, she shall not be bound by the promise: because her husband gainsaid it, and the Lord will be merciful to her.
14 If she vow and bind herself by oath, to afflict her soul by fasting, or abstinence from other things, it shall depend on the will of her husband, whether she shall do it, or not do it.
15 But if the husband hearing it hold his peace, and defer the declaring his mind till another day: whatsoever she had vowed and promised, she shall fulfill: because immediately as he heard it, he held his peace.
[Numbers 30:11-15]
Thus, Joseph accepts Mary as his wife in a platonic love transcending our physical existence. Thus, Joseph also vows chastity through his acts. Afterall what just man in Israel would touch the Ark of the New Covenant. Thus we see no customs or laws were broken.
Instead we observe this in Mary’s vow to God through the angel Gabriel “How shall this be done, because I know not man?” The New Eve, Mary, response to Gabriel is a vow of chastity. The Catholic understanding comes from the Church’s memory the historical truth that such vows were common in the first century. According to Susanna Elm, author of Virgins of God
: The Making of Asceticism in Late Antiquity, asceticism was common. Sometimes the ascetic made vows of their physical prowess, suffering training as an athlete suffers building strength. Others made vows of abstinence, perhaps limiting food or drink, not unlike fasting. One obvious biblical example is Christ's fasting for 40 days and 40 nights.
The virgin has illustrious models to follow: the five wise virgins of Gospel of Matthew, Mary, and the famous Thecla, heroine of the Apocryphal Acts of Paul. Moreover, her bridegroom is not swayed by superficiality: 'Are you bereft of parents? You are not bereft of God. . . . Have courage, because the bridegroom Christ does not regard fading beauty...whether you are short or tall' [c. Matthew 25:1-13; Apocryphal Acts of Paul 8.105- 09, [Susanna Elm, `Virgins of God' The Making of Asceticism in Late Antiquity: The Making of Asceticism in Late Antiquity]
St. Paul alludes to asceticism when he asks, “Know you not that they that run in the race, all run indeed, but one receiveth the prize? So run that you may obtain.” [1 Corinthians 9:24]. St. Paul chastised his body in self-denial in ”subjection”. Mary and Joseph lived out her vows in the customs of Judaism dedicating their lives to God. Those who practiced a divinely inspired asceticism usually take a solemn vow in the Temple; "He who takes a solemn vow contracts a spiritual marriage with God, which is much more excellent than a material marriage" (St. Thomas Aquinas, Summa). Such a vow espouses Mary to God, a vow that not even the Sanhedrin can break; only Joseph can do that.
“[The] Greek present tense used for Mary’s words in Luke 1:34 corresponds…to the Hebrew and Aramaic active participle indicating a permanent condition. Mary’s words in Aramaic were ki enneni yodaat ish, the yodaat indicating a permanent condition of virginity” (Warren Carroll summarizing and quoting from Manuel Miguen’s “indispensable” work, The Virgin Birth: an Evaluation of Scriptural Evidence (p.81) in The Founding of Christendom, Vol. I, p.310).
Manuel Miguen notices that the expression has obvious Hebrew idiomatic roots.
“It is well known that the biblical language a paraphrase to describe a virgin stricto sensu [in the strictest sense] is this: “a woman who did not know man” (Gen 19:8; Jude 11:39, see verse 37; 21:12; basically the same are Num 31:10, 35; Jude 21:11 cfr. Wisdom 3:13) – which, incidentally, shows that the same expression in Luke 1:34 points to virginity proper. These are all passages where the Bible refers to women who “did not know man.” Miguen continues to point out how interesting the present tense is never used with regard to virginity in the Old Testament. Miguen further suggests that the Greek translation makes the best of the Aramaic it can by using the Greek aorist tense. [source
The virgin birth : an evaluation of scriptural evidence : Miguéns, M. (Manuel) : Free Download, Borrow, and Streaming : Internet Archive ]
Consequently, we hear Mary to vow before the emissary of God, (in my words), ‘How can this be when I did not know a man, do not now know a man, and will never know man. ‘ Mary vows virginity in the presence of a Divine Messenger as well as expressing her own astonishment.
JoeT