Dear Mamabear,
This is a good topic. I know the feeling of loneliness even when surrounded by people. It´s well known, and it´s one of the most difficult feeling to deal with.
When I was married I had this feeling a lot. Sometimes I get it when I´m surrounded by my family and everyone is married or engaged. But it´s bothering me less and less. It´s really the state of mind.
I think the answer is making a rich, full life for ourselves. Then this feeling won´t be as common and definately not as overwhelming.
Love and light,