Marriage does not, imo, endorse one's commitment to another person. My fiance and I were engaged for 13 years and, in retrospect, I am glad we didn't marry (my choice), as the break up would have been made more upsetting and difficult. Had we had children, I would have wanted to be married, but that is personal choice. If both partners are accordant with the situation, and are happy with the relationship, why change it? When I was at school, a stigma was attached to single mothers. These days, they outweigh married parents. If Michelle was unhappy with things as they are, she wouldn't be with him. Obviously, it's working fine for them. As the majority of contributors to this post have said, whose business is it anyway?