Recognition of sexual and gender diversity in the 21st century challenges normative assumptions of intimacy that privilege heterosexual monogamy and the biological family unit, presume binary cisgender identities, essentialize binary sexual identities, and view sexual or romantic desire as necessary. We propose a queer paradigm to study relationship diversity grounded in seven axioms: intimacy may occur (1) within relationships featuring any combination of cisgender, transgender, or nonbinary identities; (2) with people of multiple gender identities across the life course; (3) in multiple relationships simultaneously with consent; (4) within relationships characterized by consensual asymmetry, power exchange, or role-play; (5) in the absence or limited experience of sexual or romantic desire; (6) in the context of a chosen rather than biological family; and (7) in other possible forms yet unknown. We review research on queer relational forms, including same-sex relationships; relationships in which one or more partners identify as transgender, gender nonbinary, bisexual, pansexual, sexually fluid, "mostly" straight, asexual, or aromantic; polyamory and other forms of consensual nonmonogamy; kink/fetish relationships; and chosen families. We argue that a queer paradigm shifts the dominant scientific conception of relationships away from the confines of normativity toward an embrace of diversity, fluidity, and possibility.