On the subject of eternal marriage and our calling and election made sure, Bruce R. McConkie wrote,

“Making one’s calling and election sure comes after and grows out of celestial marriage. Eternal life does not and cannot exist for a man or a woman alone, because in its very nature it consists of the continuation of the family unit in eternity. Thus the revelation on marriage speaks both of celestial marriage (in which the conditional promises of eternal life are given) and of making one’s calling and election sure (in which the unconditional promise of eternal life are given) in one and the same sentence.”

 Doctrinal New Testament Commentary 3:343