Good question. Simplest answer is that a man may be married for eternity with more than one woman - current 'interpretation of D&C 132. Get past that and the whole scheme gets very twisted.
OK, you addressed what happens with a man. He is allowed multiple wives in the next world, but what if I’m a Mormon woman and I am widowed and remarry. Let’s say I die at a very elderly age and have had a total of 3 husbands on this world, who gets me in the next? Do I have any choice in the matter?