There are many, many problems with the approaches taken in the so-called “social sciences” and clarity is rarely achieved in consequence. If we take the example of interpersonal relationships it becomes clear that we need to separate out a wide range of contributing factors in order to achieve any kind of clarity and understanding. One of the great boons of evolutionary psychology is that it can enable the scientific method to be applied (hypothesis that makes unique testable predictions that are at variance with other ideas) whereas all other social sciences are merely observation and assertion.
If we take relationship dynamics we can see how this works. Looking back at the conditions pertaining to our ancestors it’s pretty clear that a female would have a clear biological imperative to abandon a wounded mate (yesterday’s meal won’t feed tomorrow’s empty stomachs) and in order to be ready to mate with a more viable male she’d need to erase her previous mate from her consciousness as much as possible. We can hypothesize therefore that women will tend to look negatively (if at all) on the prior relationship whereas men will be less inclined to do so. Bitterness may be present on both sides but the unique prediction here is that for females there will be greater emphasis on the “bad” aspects of the relationship and far greater overall forgetting than is evinced by males.
The point is, this is a testable hypothesis, not an opinion or a mere assertion. It can be tested and either proven or disproven by means of an adequately designed and conducted experiment.
Likewise one can create evolution-based hypotheses about the characteristics of each phase of a new relationship and then test these hypotheses also. One can test notions about unconscious non-verbal signaling, unconscious aspects of mate attraction, and so forth. The key point here is that to date most psychological notions have either been assertion-driven or the result of very poorly designed studies. The “science” part of “social sciences” has for the most part been conspicuous by its absence. We should consequently be very cautious about how much credence we are prepared to grant to what we find in the academic literature.