Some scientists sometimes may have different opinions - but God created a man and a woman and then those two created lots of girls and boys to grow up as man and woman - 1:1 - for each girl a perfect lover-man has been created - for each boy a perfect lover girl has been created as well.
The day we are truly grown ups and ready to love - and only to love - that day we shall be ready to recognize the lover made by God. One single person sufficient to make you happy all eternity. Only a single person can do so - if 2 or more try to make you happy all that will result is a huge mess of jealousy, envy, distraction and loss of peace.
To find the one God created you have however to accomplish all your own homework first. For most humans the magic encounter shall be at home in God - after completion of all your homework learning to love like a child of God. Anything else here and now on earth mostly is a waste of time due to your impatience to wait until you have done all your own homework as well - to wait until you are a grown up child of God. Most relationships encountered on earth are but wrong partners to make you aware of the need for the right one and to create or awake your own readiness to spiritually grow up and progress.