Excellent theory, mgus! This would mean that the harder it is for her to get orgasm, the more selective it works. She has to go through a lot of guys to find the right one for her. The only difficulty with the theory is that in ancient times, this search process would lead to become pregnant with many different fathers, thus having many kids. Few of them would survive without quickly finding that trusting partner to support them.
Nowadays with contraceptives we are less likely to see this, we just see the end result: the long lasting relationship. Maybe it is possible to verify scientifically that the serious relationships tend to last longer if the woman does not orgasm very easily. She will have a lot of short test drives in the beginning of her sexual career of course, then settle for the one that can satisfy her. Intriguing to speculate about the wider consequences. When she finds that ‘unique’ man who is able to get her to orgasm she tend to become emotionally attached to him for life, and is less likely to cheat - she believes from experience that no other man can satisfy her like her life partner.
Who is that guy? We already know that he is enduring, skillful and caring, maybe he also has a heavier ball sack than the rest as useful instrument of making her reach orgasm. For us PE’ers, however, the critical question is how big penis he is likely to have.
Is he likely to be extremely well endowed? Probably not. With a large piece and the importance that is attached to it, that guy finds it tends to attract girls with little effort from his side. He can pick and choose. There is always another one if she turns out to be ‘lousy in bed’, i.e., unable to enjoy his valued equipment and get orgasm. Besides, she will not feel satisfied either.
If this reasoning is correct, the guy in long lasting relationships is likely to have an ‘average’ penis, broadly defined. In principle it would be perfectly alright with a really small one, but since that affects confidence negatively due to the value that HE attaches to it (not she because she knows better from experience), he will not be able to be the secure life partner she seeks.
Conclusion: next time you see a girl that tells you she have had guys with larger dicks, smile. Since she obviously didn’t stay with any of them, she might have be looking for just the qualities you have to get her satisfied.