Your spouse can be a friend to your sexual needs

 A friend can use his stability and strength to make one full of joy and ones joy full.

And a friend can use her beauty and delightfulness to comfort and sustain you.

One can trust them and they can be a friend to this need in your life, They can be your home. One can depend on that. One can surrender as you get closer. They can treat you special. One can find rest and joy in love, and trust them to love you, as you enjoy their love. One can delight in their love and treasure it. Take joy in the love the wife/husband of your youth and be ravished in their love.

Therefore your spouse is supposed to be your friend.