Yep, I was essentually right. According to The Utah Code:
78-30-1. Who may adopt -- Adoption of minor -- Adoption of adult.
(1) Any minor child may be adopted by an adult person, in accordance with the provisions and requirements of this section and this chapter.
(2) Any adult may be adopted by another adult. However, all provisions of this chapter apply to the adoption of an adult just as though the person being adopted were a minor, except that consent of the parents of an adult person being adopted is not required.
(3) (a) A child may be adopted by:
(i) adults who are legally married to each other in accordance with the laws of this state, including adoption by a stepparent; or
(ii) any single adult, except as provided in Subsection (3)(b).
(b) A child may not be adopted by a person who is cohabiting in a relationship that is not a legally valid and binding marriage under the laws of this state. For purposes of this Subsection (3)(b), "cohabiting" means residing with another person and being involved in a sexual relationship with that person.
No wonder children aren't finding quality homes. They've narrowed the field so much.
http://adoption.about.com/od/adoptionlawsbystate/