1Sunken Costs and Desired Plans: Examining Different Types of Investments in Close Relationships Wind Goodfriend

purpose of the present work is to examine intensively one factor known to promote relationship stability, invest-ments, and to offer a new conceptualization of investments focusing on their timing and materiality. Investments in Relationships The concept of investments in a romantic relationship is a cornerstone of one of the most researched theories of relationship stability, Rusbult’s (1980a, 1983) Investment Model. In this model, based on concepts from interdependence theory (Kelley & Thibaut, 1978; Rusbult, Arriaga, & Agnew, 2001; Thibaut & Kelley, 1959), the level of one’s commitment to a relationship influences relationship stability. Commitment is the sub-jective state of dependence that individuals experience daily regarding their relationship (Agnew, Van Lange, Rusbult, & Langston, 1998). Commitment is hypothe-sized to be a function of three interrelated factors: (a) the level of satisfaction with the relationship (or the degree to which relationship outcomes are experienced as grat-ifying); (b) the quality of a relationship’s alternatives (or the perceived desirability of the best available alternative to the current relationship); and (c) the size of invest-ments in the relationship. Investment size is defined a