Male and female sexual energy
In a field of duality you carry unequal balances of male and female energy.
The nature of the Universal Energy is to seek balance and the balance of male female sexual energy is what is now before you as humans.
As a result of this imbalance, your sexual energy is strongest when another soul reflects your energy with the balance of their own.
This is the nature of sexual relationships.
The base energy of all energies is felt in human form as Love.