Past research on commitment processes in close relationships has tended to adopt a dichotomous view of relationship persistence, yoked to the type of relationship under consideration. A relationship is either on or off, together or broken up. We argue against such a view, reasoning that close relationships are more suitably char­ acterized by frequent changes in type of relations between dyad members. Little is known about how relationships may morph from one type to another, such as from a steady romantic relationship to a friendship (or vice versa). This chapter considers how people contemplate relationships with alternative others as well as alternative forms of a relationship with a current relationship partner. We focus our discussion on the concept of need fulfillment, noting how needs might be filled by different partners or by different forms of a relationship with a given person. Using the Bases of Relational Commitment Model, a new model that extends the well-known and validated Investment Model, we articulate a theoretical framework that iden­ tifies how thoughts about other forms of a relationship with a partner might help account for relative commitment to the current type of relationship experienced by dyad members. We close by describing some methodological challenges to con­ ceptualizing relationships as dynamic and subject to change.