Tron

ChronoTrigger: D&C 131 really explains that there are three sub-degrees within Celestial Kingdom. It does not mean they are split realms (like paradise and prison). All "citizens" of Heavenly Kingdom will be living within the same plane as Heavenly Father, Christ and other heavelny beings. But there will just be a major difference in destiny of eternally married couples (who righteously kept all covenants and promises made in connection with this bond) and those who did not join with any spouse. It is revealed and explained in D&C 132 that only righteous couples may reach to the highest blessing of Exaltation. The reason is simple; God the Father could not be called a father if He would not be joined with a Mother to have us as spirit children (see also Family Proclamation, that we are children of heavenly parents) - that is his greatest joy and happiness. And He wants for his children to obtain all He has, that also includes being able eventually join in creating spiritual children and create worlds without end for them so that also they may reach this kind of highest joy. That is why marriage and family is so important and why Satan tries to destroy this sacret institution. That is what is meant by "increase" in D&C 131:4. It means eternal increase of posterity, which is only possible if a man and a woman are sealed by God's priesthood power and then ressurected to celestial bodies - that is a stipulation of being able to have spiritual children forever. Logically this is not possible for an individual alone.

Yes, sad for the family. Do you know the book from Duane S. Crowther: Life Everlasting? It is a compilation of lds life after death experiences with quotes form authorities on this topic. One thing mentioned there, very interesting to me, was that God might actually end someone's mortal life sooner to call the person up to do the missionary work in the spirit world