Why do I not find success in marriage despite repeated engagements and their failure?

Marriage, like other matters, is predetermined and is a provision (rizq). There is no need to worry about a delay in marriage, as it might be due to a normal reason. If it is due to magic (sihr), then its cure is through ruqyah shariyyah (Islamic exorcism). It is preferable to perform ruqyah on oneself. If you need someone else to perform it, let it be a person of rectitude, and beware of magicians and charlatans. A woman can seek a righteous husband and offer herself to him.