What you are feeling is the simple need that Abraham Maslow failed to document.Human beings have the Frontal cortex that is too complicated and evading clarity to the best of scientists and researchers still.
I have no clue as to where the writer of Patanjali Yoga Sutras was able to go inside and report so much about that portion of the anatomy.
What you need is to be wanted and fulfilled in the sense that you do things for someone and that someone does things for you. It need not be in equal proportions, but just doing it to give satisfaction with no expectations.That social relationships between two or more people can be built for a short duration in animals for a few months in mammals and for a very very long time in Human beings. It can even survive the demise of one of the partners.
In Hindu mythology when a marriage is done the vow that they take is to be Man & Wife for seven incarnations. It might sound too hollow but is a fact that has stood the test to time and over centuries of coercive conversions .
This belief of seven lives of wedlock is still prevalent and in practice.
The human being is neither the body , nor the soul but a culmination of the body the soul and the intricate relationships he weaves. You can not prove them but see them exist. You just connect to people and build the relations and cherish them as a sacred part of your life.