When is the al-Siddiqah to fulfill her vow of fasting three days, given that she made this vow if she became engaged, and she has been engaged more than once but the marriage did not take place, and she does not remember if her intention was only the engagement or the engagement and the marriage?

Vowing is prohibited, but whoever vows an act of obedience must fulfill it. The essence of a vow lies in its meaning and intention. If the one who makes the vow doubts their intention, they should act upon their predominant presumption, recalling the reason for the vow and their state at the time. Vows and oaths are from the same category, so the expiation for a vow is the same as the expiation for an oath. If neither side of the doubt prevails, one refers to the apparent wording, and fulfillment becomes obligatory. If a woman forgets her intention, she should act upon her predominant presumption. If nothing prevails, she must fulfill the vow conditioned upon the engagement taking place, which would be fasting for three days. If she fulfills her vow each time an engagement occurs, that is good.