Well, what happens if you die when you're twenty, unable to marry anyone for eternity (you're LDS.) I believe that you can still go to the highest degree of the celestial kingdom. God will give you a partner (a friend be it), and the two of you can be sealed. Then you can go and create worlds together
What my question is: is why is it that if a man gets the degree of celestial, and a woman terrestrial, she'll go with him in his kingdom. But, if a woman gets celestial, and a man terrestrial, he'll be left behind?

Meh, it might not even be true. I just sometimes feel very feminist about certain things.