Total hogwash.
Statistically speaking if there were only one true soulmate out there, then 99.999999999% of all people getting married are not with their soulmates because the chances of that many people finding their "one true love" is incredibly tiny. You are more likely to win the lottery then to actual meet/court/marry the one person out there that is intended for you.
On top of this, since people change during the course of their lives, what they want in a partner now may not be the same as what they want in the future or wanted in the past, so that being the case that perfect person may not be so well suited in a different scenario.