I have heard that Saint Joseph made a vow of virginity in addition to Mary’s own vow. Her vow of virginity is very clear in Luke 1:34, but the best arguments I’ve heard for Joseph’s vow have been either “Well, she made one, so Joseph must have just gone along with it!” or “Clearly, they would have talked about it before getting married, so her vow of virginity must have come up. If he hadn’t also made a vow, he wouldn’t have betrothed her.” Both these reasons seem to base their conclusion on modern ideas of communication prior to marriage, which was so radically different between the sexes in the time of the Holy Family.
Biblically, can we know if Joseph made a vow of celibacy prior to becoming betrothed to Mary? How do we know this?