I think that part of the story has been missed. While in some cultures, an old man marrying a young girl would be ordinary, I suspect that at the time, among Jews, it was thought of as extraordinary.
That is, not frowned upon, but unusual, or done for unusual reasons. In this case, Mary’s parents, Joachim and Anna, were already elderly when she was born, which suggests that they died when she was still at a young age.
Girls in that time were considered as marriageable at the age of 12 years and six months. So even with a vow of chastity, as an orphan she would be more or less “assigned” for marriage to a man, so she would not starve to death, though she could choose from among candidates. And he would know that she had made a vow of chastity.
Where is your evidence Mary ever made such a vow?
And Mary's brothers and sisters were all virgins til death as well and so was Anna...It ran in the family...
Anna loved German chocolate cake and fed it to the kids constantly...That's why Mary was an extremely chubby child...She grew up so chubby that her husband had to haul her around on a Donkey...
Just like yours, my story has no basis in fact either...