However, hormones alone are not enough to achieve attachment. Purely psychological factors play an important role. For example, how long was the process of courtship and conquest of a woman. The longer the candy-bouquet period was, the strangely enough, both lovers consider their partner more valuable.
By the way, this phenomenon is well described by the game theory. This is an example of the so-called signal game, in which players exchange observable actions that reveal their features. By convention, any man in a competition for a woman wants to show that he is the best and most worthy of her choice. However, he may be a simple playboy who wants one-night stand. It's important for a woman not to make a mistake with the choice, since if she becomes pregnant from a playboy, then she'll have to bear all the hardships of raising a child alone. Therefore, a woman should choose the most reliable man. But how to do that?
Mathematically, the playboy's maximum gain is to get a woman as quickly as possible and spending a minimum of resources. The woman has the maximum gain - to get a long-term partner who will share with her the hardships of raising their common offspring. The "good guy" has a similar gain. Therefore, it is possible to separate the grain from the chaff only by dragging out the courtship process as much as possible, forcing both competitors to waste time and resources. In this case, the womanizer will quickly disappear, as he will understand the futility and cost of this approach. It's easier for him to switch to a more affordable target. A truly in love "good guy" will signal with his perseverance and willingness to invest resources in a woman the purity of his intentions.
Among other psychological factors that help maintain long-term attachment for decades, a central role is played by the initial idealization of the object of love. In this case, we more easily forgive the partner for the discovered flaws, since their image in our head is stronger than real circumstances. It's also very important that there's an extensive baggage of life experience shared together: travel, shared business and achievements, and sometimes even adversity and difficulties.