Being married in the temple for “time and eternity”, which is essential for exaltation. It is also called eternal marriage. It is also performed vicariously for the dead.
“The major crowning point of the law which man must obey is eternal marriage. Therein lies the keys of eternal life or, as the Doctrine and Covenants puts it, ‘eternal lives.’ In other words, an eternal increase of posterity” (Achieving a Celestial Marriage Student Manual, p. 4).
Biblical Christianity teaches that there is no marriage in heaven (Luke 20:35-36). Our heavenly relationships will greatly surpass any earthly relationship.