Gender Roles

Most people would tend to describe female tendencies as:

Emotionally expressive, cooperative, detail-oriented, relationally-oriented (how things are in relation to each other), and typically better at language and writing.

Most people would tend to describe male tendencies as:

Physical/aggressive, competitive/active, gross-oriented (sees things in the "bigger picture"), spatially/task-oriented, and typically better at mathematics and logic. 

That being said, there's ALWAYS people who are an exception to the natural tendencies, and there's also a range of each "category." It's ok if someone is different than the "typical" male or female, that's what makes us all different and unique. We have to be careful not to treat them different because we think they are "different."

So if men and women are so different, why would God assign/demand that they create a family together?

I think President Gordon B. Hinckley put it beautifully when he said, "In His grand design, when God first created man, He created duality of the sexes. The ennobling expression of that duality is found in marriage. One individual is complementary to the other. As Paul stated, 'Neither is the man without the woman, neither the woman without the man, in the Lord' (1 Corinthians 11:11). There is no other arrangement that meets the divine purposes of the Almighty. Man and woman are His creations. Their duality is His design. Their complementary relationships and functions are fundamental to His purposes. One is incomplete without the other."

Men and women are pretty much opposites to complement each other. Based of The Family: A Proclamation to the World, women are best fit to be the nurturers of the children and men are to provide for, protect, and preside over the family. That doesn't mean that the husbands and wives don't help each other. Husbands and wives are supposed to be equal partners and work as a team to make their family work. It's amazing because our tasks/abilities go along with how our brains tend to be wired. 

Husbands and wives round each other out and are able to provide both sides of the spectrum. If this wasn't the case, we wouldn't be able to reach our full potentials and help each other learn and grow. For example, a wife may be more detail-oriented and focusing a lot on the here and now. The husband can them come in and help her see the "bigger picture." This also goes for the children as well as the parents. Children need both parents to be able to create the perfect environment for them to learn and grow.

Here's a funny explanation of male and female brains called, The Tale of Two Brains.

https://www.youtube.com/watch?v=3XjUFYxSxDk