The Female's Internal Conflict

It is built into our very nature as human beings to have to endure the conflict imposed by the combination of our biology and rationality, our bodies and our minds. For reasons that are beyond our abilities to completely understand, our minds work in such a way that we are driven by pride, while our bodies operate according to their inclinations to reproduce and (presumably) perpetuate the species. These two drives often push us towards opposite goals, resulting in a conflict that is reflected - perhaps at its strongest - in the dating world.

As a woman, your pride wants a man who values you above all other women, one who would do anything for you out of an overwhelming compulsion of feeling. You (like every person) need to know you are valuable and important, which is largely evidenced by feeling wanted.

Your biology, on the other hand, aches for a man who is strong and powerful, unfettered by his feelings, who can protect you and impregnate you with healthy children - children who in turn will survive and reproduce successfully.

But the fact is that men also have biologies that drive them, almost uncontrollably. They desire the most beautiful and healthiest women - those most capable of bearing their children. This means that the men who best fulfill the needs of your pride are those who are farthest below your league, and therefore want you most. But at the same time, almost by definition, the men who best fulfill the needs of your biology are those who are farthest above your league, and therefore want you least.

The reality is that - eventually, after all efforts at self-improvement - you have to choose a man who represents a balance between those two extremes. If you want a man who values you immeasurably, he isn't going to be the heroic hunk you desire sexually. If you want a man who can provide you with perfect babies, he isn't going to want you above all other women - because he probably can have all other women (at least all those at "your level").

Two factors mitigate the apparently unfortunate nature of this situation:

1. Men are faced with a similar conflict, and they too have to compromise, meaning that the object of your biological desires has fewer women to choose from if he wants a girl that also loves him as a person. Perhaps more important than the needs of his pride is the fact that he cannot have a woman that doesn't want him. Your best possible partner will be one who recognizes this, values your love for him, and is willing to curb his desire for other women because of it. Still, the fewer options he has to forego, the easier (and more likely) this commitment will be for him to make and maintain.
2. All men and women have different tastes when it comes to the opposite sex, so a single woman sits very differently on various men's scales. This is why I've placed "your level" in quotation marks above; is relative to each man's personal taste.

Admonitions not to "settle" are actually admonitions against settling too much - against choosing a man that doesn't fulfill one of these two needs sufficiently. In reality, we all settle in the sense that we settle for a man or woman that fulfills both of these needs, but fulfills them both only partially. No single person can fulfill both completely because the two sets of character traits that do so are (with the above caveats) mutually exclusive.