However also important is an understanding of what PNC is. It’s the reduction of levels of hormones and dopamine after finishing. Thereby, yes it always happens after sex. However, this also means that if these hormones and dopamine were the things fueling the encounter (as would be the case if it was solely a physical attraction) the subsequent reduction can end up causing a loss of interest or attraction. However when these guy actually LOVES the woman, the chemicals only play a backseat role.
Given your reply to the other comment this seems to be from a place of personal experience with somebody who had a one night stand when you wanted more, or your perspective of male promiscuity is skewed, many men are loyal, but the men that tend to “attract” the most girls are the frat, tall, douchey ones. This makes alot of girls think all guys are this way, when it is far from the case.