The field of interpersonal relationships would benefit from overarching approaches that explain multiple interpersonal relationship phenomena such as initiation, maintenance, and dissolution (Reis & Mizrahi, Reference Reis, Mizrahi, Vangelisti and Perlman2018). We commend Kruglanski and colleagues for proposing a unifying framework. We also identify two areas of ambiguity to address so that it can thrive as a theory: (1) improve its testability and falsifiability and (2) make it generalizable.

Regarding testability and falsifiability, falsifiable theories forbid events from occurring (Popper, Reference Popper1959). The current model suggests that “love serves the fundamental human need for significance and mattering” (p. 4). This implies that without a quest for significance, there would be no love. However, as a fundamental need, quest for significance cannot be 0 – which would be the level necessary to allow for falsification, or finding instances where love exists independent of significance quest. As quest for significance is suggested to be the cause of love, an inability to test this assumption renders the core tenet of the model unfalsifiable.

Similarly, it is unclear whether any observations can falsify the “merit” parameter of the model. First, the model lacks a clear, a priori specification for how a partner is perceived as meritorious, instead defining merit as anything the actor finds desirable. Second, merit is framed as a means for significance, although a partner who fulfills one’s significance quest should be “desirable,” and consequently, judged as meritorious. Which observations are forbidden? Falsification would require either observing love in the absence of perceived merit or not experiencing love in the presence of merit and the other components of the model. Without clarifying how merit is determined, any observations can be explained post hoc by designating a partner as meritorious or not.

The same applies to the “acceptability threshold.” The model proposes that two different formulas for love could apply: Love is a multiplicative function of significance quest, merit, and appreciation if these parameters fall below “an acceptability threshold”; however, above the threshold, the function is additive. This assumes different functions for different domains or values of the parameters, further implying two distinct mechanisms. However, an ambiguous acceptability threshold creates a mysterious “black box” at the core of the formulation (i.e., how is the acceptability threshold determined?). The model’s testability could be strengthened by explicating under which conditions each function should be used, allowing for predictions that can be empirically tested and falsified.

The second limitation relates to the model’s generalizability. The model’s focus on quest for significance as the driving factor of love ignores research suggesting that other fundamental needs – survival and reproduction – are psychologically and biologically connected to the experience of love (Shih et al., Reference Shih, Kuo, Wu, Chao, Huang and Huang2022). Social needs evolved to foster survival and reproduction (Alexander, Reference Alexander1974). Thus, partners should be, above all, directly instrumental to these fundamental needs. Indeed, partner selection and the types of relationships people pursue are influenced by the extent to which such partners and relationships fulfill different adaptive needs (e.g., sexual accessibility, resource investment; Buss & Schmitt, Reference Buss and Schmitt1993). Additionally, pair-bonding in both humans and non-human animals uses similar neurobiological processes (Blumenthal & Young, Reference Blumenthal and Young2023; Walum & Young, Reference Walum and Young2018), suggesting that feelings of love may exist without the quest for significance.

The proposed model essentially reduces love to a singular, ultimate cause. A broader motivational approach to multiple interpersonal phenomena is more beneficial than focusing on love as a unique phenomenon specifically driven by one’s significance quest. Such an approach should explain one’s liking or preferences for certain partners while acknowledging that these preferences are dynamic, as evidenced by phenomena of falling in and out of love, infidelity, etc. Phylogenetically and ontogenetically, humans experience positive affect toward objects, behaviors, and people that fulfill their needs (e.g., attachment bonds) and experience negative affect toward objects that interfere with their needs. When a means is effective for goal progress, a transfer of affect occurs wherein positive affect elicited from goal attainment is transferred to the means, or an instrumental partner (Fishbach, Shah, & Kruglanski, Reference Fishbach, Shah and Kruglanski2004). Although positive feelings can emerge from one’s progress toward their significance quest, positive affect should also emerge from any goal for which the partner is instrumental. Indeed, people report having higher relationship satisfaction and feeling closer to individuals who aid in the pursuit of various goals, including sexual, social support, and health goals (Fitzsimons & Shah, Reference Fitzsimons and Shah2008; Orehek, Forest, & Barbaro, Reference Orehek, Forest and Barbaro2018).

Is a need-content model the strongest theory to adopt, or could a theoretical focus on one specific need inadvertently limit the potential for new discoveries? A content-agnostic motivational framework that acknowledges partners can serve multiple goals that change in importance may be better suited to explain not only love but also other phenomena. Such a framework should better predict partner selection, in that a person should be preferred based on their instrumentality to important, active goals at a particular point in time (Fitzsimons & Fishbach, Reference Fitzsimons and Fishbach2010). Although these lower-order goals may ultimately serve one’s desire for significance, these goals may be more proximal predictors of behavior. A framework that acknowledges the multitude of goals that a partner can serve, as well as their dynamism, can also capture various changes in relationships. For instance, if a goal arises for which one’s partner is not instrumental, one might seek alternative means (i.e., partners), in some cases leading to infidelity and relationship dissolution. However, upon fulfillment and de-activation of that goal, new needs arise for which a partner may be again perceived as instrumental, prompting feelings of remorse or rekindling of the relationship (Allen & Atkins, Reference Allen and Atkins2005; Dailey et al., Reference Dailey, Rossetto, Pfiester and Surra2009).

To conclude, we believe that the authors’ attempt to highlight the motivational underpinnings of romantic relationships demonstrates the need for unifying theories in relationship research. However, its reductionist approach includes ambiguities that require clarification in order to be a major theory. We argue that it would be more advantageous to use a broader motivational framework that considers the multiple goals a partner can fulfill, and how these dynamically shift in importance to shape interpersonal feelings and associated phenomena.