People fall in love because they love each other's company
True love is about commitment, being there through sickness and in health, and creating a meaningful friendship underneath the romantic elements. Some people fall in love because their partner is someone they can laugh with and cry with.
This happens because our brains and hormones go wild when faced with a sincere love interest. "When we are in the company of the loved one the brain produces more serotonin, which gives a sense of well-being, more endorphins, which are natural pain killers, and more dopamine, which increases pleasure.