Because a significant amount of the Masechta is dealing with the beginning of Parshas Matos (Bamidbar 30:2-17) which discusses a husbands ability to husbands ability to anul his wife's vows.

Because a significant amount of the Masechta is dealing with the beginning of Parshas Matos (Bamidbar 30:2-17), which discusses a husband’s ability to annul his wife's vows.