Martha M. Ertman has written a number of papers on the need for "new vehicles" for personal contracting. As I recall, Ms. Ertman mentioned the Relationship LLC in one of her publications.
CLICK HERE for excerpts from Martha M. Ertman's "The Business of Intimacy" in the online book "Feminism confronts homo economicus: gender, law, and society By Martha Fineman, Terence Dougherty"