They weren’t my thoughts but I’ll help you out…
To begin with, the Protoevangelium records that when Mary’s birth was prophesied, her mother, St. Anne, vowed that she would devote the child to the service of the Lord, as Samuel had been by his mother (1 Sam. 1:11). Mary would thus serve the Lord at the Temple, as women had for centuries (1 Sam. 2:22), and as Anna the prophetess did at the time of Jesus’ birth (Luke 2:36–37). A life of continual, devoted service to the Lord at the Temple meant that Mary would not be able to live the ordinary life of a child-rearing mother. Rather, she was vowed to a life of perpetual virginity.
However, due to considerations of ceremonial cleanliness, it was eventually necessary for Mary, a consecrated “virgin of the Lord,” to have a guardian or protector who would respect her vow of virginity. Thus, according to the Protoevangelium, Joseph, an elderly widower who already had children, was chosen to be her spouse. (This would also explain why Joseph was apparently dead by the time of Jesus’ adult ministry, since he does not appear during it in the gospels, and since Mary is entrusted to John, rather than to her husband Joseph, at the crucifixion).
According to the Protoevangelium, Joseph was required to regard Mary’s vow of virginity with the utmost respect. The gravity of his responsibility as the guardian of a virgin was indicated by the fact that, when she was discovered to be with child, he had to answer to the Temple authorities, who thought him guilty of defiling a virgin of the Lord. Mary was also accused of having forsaken the Lord by breaking her vow. Keeping this in mind, it is an incredible insult to the Blessed Virgin to say that she broke her vow by bearing children other than her Lord and God, who was conceived through the power of the Holy Spirit.
This is found at catholic.com/library/Mary_Ever_Virgin.asp