There are many rules in astrology to find out correct prediction about marriage. Seventh House of horoscope, Jupiter, Venus, Mercury and Moon's period, 7th house lord's period or sub period generally becomes the reason for marriage.
You get marriage proposals when auspicious or benefic planets rises in your horoscope. You get marriage settlement when a planet who's period is running right now is connected with seventh house in horoscope or Varshfal.