The very notions of short- and long-term couples conceal in fact a variety of situations that are difficult to categorize by means of such a generic terminology. There may be long-term couples characterized by situations of substantial exploitation or abuse of a partner over the other, which are kept stable by a certain socio-cultural context, and there may also be short-term couples whose cause of dissolution is not of an opportunistic nature but, to the contrary, is altruistic, such as in the case of the operation of the moral responsibility filter that leads a tied-up partner to leave the couple to altruistically prevent the other partner from suffering a major damage. More than the couple durability, the conceptually distinctive element to structure a taxonomy of couples seem to be that of the existence (or of the failed existence) of the TU, and its possible unilateral or bilateral nature.

It is clear that to test its descriptive and predictive validity, this approach needs to go through an extensive experimental check. A first research path of some interest is that of the analysis of narrative corpora characterized by a certain level of social validation, which thanks to the social cognition valence of fictional narratives may provide a first test bed to check to what extent the structure of socially validated romantic narratives tends to reflect the implications of the tie-up theory. Early analyses carried out on some of the most successful Hollywood romantic comedies of the last decades and on the main romantic fairy tales offer a first, albeit preliminary, corroboration of the theory, thus encouraging further research on the topic. It is now necessary to develop an experimental strategy as well, which takes into account the caveats already brought out in the previous discussion, namely avoiding the elicitation of the preferences of the subjects in an abstract context and in a plainly artificial situation. A wave of experimental studies that are robust against this type of criticism are therefore called for, and this is certainly a challenging task for future research. Some alternative paths may be those of the semantic analysis of individual accounts of real within-couple experiences, or, in a complementary rather than alternative logic, the measurement of the psycho-neuro-endocrinological response to certain stimuli targeting the conscious and sub-conscious reward systems of experimental subjects, so as to highlight possible distinctive signatures of the activity of the AAs and RAs. This would help to overcome the limits of an elicitation based upon self-perception and self-representation, to directly probe into the circuits of the bio-behavioral programming of mating choices.

In light of the big research effort put in the last decades into the topics of the formation and stability of human heterosexual couples, we believe it is important to stress the necessity of a theory that does not conceptualize the choices related to couple formation in terms of abstract categories of desirability or of artificially restricted sets of motivations. Instead, there is a need to develop increasingly sophisticated tools to understand how the combination of the characteristics, expectations, and desires of two specific potential partners, and their direct interaction, may be conducive or not to the formation and stability of a more or less cooperative, fusional, and accomplished couple, as opposed to opportunistic, or based upon exploitation, or upon constriction.

Author Contributions

Formal analysis, L.L.B. and P.L.S.; Investigation, L.L.B. and P.L.S.; Methodology, L.L.B. and P.L.S.; Writing-original draft L.L.B. and P.L.S. All authors have read and agreed to the published version of the manuscript.

Funding

The conscious level tends however, as already remarked, to emphasize the objective desirability of certain individual traits, rather than to embed them within the dynamic framework of a specific relationship, where the combination of the individual characteristics of the involved partners is highly personalized and essentially unique. The match between the partners’ ideal models is not an objective, fixed feature, ruled by the presence/absence of a specific desirable trait, but is rather a process where each trait is considered and assessed within the overall bundle of partner characteristics . A process-based vision of the ideal match between partners may be rather conceptualized as a (hard to achieve for real couples) shared pathway of mutual harmonization of psychological characteristics . One should moreover observe that those ‘abstract’ individual and social standards of desirability are themselves far from immutable, and evolve at a speed that may widely differ across socio-cultural contexts . The very balance between (dynamic, processual) partner compatibility and the desirability of the other’s personal characteristics on the basis of abstract individual and social standards is struck differently in different socio-cultural environments . These highly specific contextual aspects of the human mating process may be appreciated with some difficulty by the theoretical approaches that focus their attention on abstract desirable characteristics, disconnected from concrete relational settings.

The dynamic reciprocal adaptation between partners in the mating process, whatever its outcome, may open up very diverse interaction scenarios, which may entail very different levels of mutual cooperation in the construction of a couple bond. What distinguishes the most solid and resilient forms of human mating is a form of super-cooperation, where the partners are willingly locked into a stable cooperation mode with altruistic components , which in the language of the tie-up theory will be defined as a double tie-up. The altruistic dimension that makes such super-cooperation more stable than other couple bonds is not innate but dynamically built through a highly adaptive process that we will call the tie-up cycle. One can find forms of cooperation between partners also in couples where no tie-up is normally observed, such as, for instance urgent link, in couples formed through combined marriage or in couples that are formed for convenience, e.g., to escape the control of the families of origin. However, such forms of cooperation do not present altruistic components and are more fragile with respect to external circumstances. The adaptive value of a super-cooperation between partners is instead that it offers a particularly stable, resilient environment for the joint rearing of the offspring.

The structure of the remaining sections is the following. Section 2 presents a brief discussion of the literature that tends to approach the mating process as a result of opportunistic choices with an implicit adaptive value, and of the limits of such an approach. In Section 3, we analyze the relationship between the cooperation within the monogamic couple finalized to the joint rearing of the offspring, and the dimorphism of the mechanisms that get men and women to bond into a stable couple, as characterized by the tie-up theory. In Section 4, we present and briefly discuss some of the main categories of filter tests. In Section 5, we introduce the mating stability matrix and briefly present its characteristics and main implications. Section 6 provides a final discussion and concludes.

Women appreciate men with a wide spectrum of compatibility both in sexual and psychological terms, as this is not only an index of a genetic endowment that is generally valued at the community’s level but is also a sign of a subject that carries highly rated salient (for the F-AA) psychological traits .