Not to draw out the xNFP controversy, but I wondered why you think that some xNFPs will be "wallflowers" in their youth before displaying more freewheeling behaviors like infidelity? Wouldn't one expect to see the opposite, as older xNFPs grow into their Si/Te, which are generally considered more settled and reliable functions? Just curious.
To understand what happens it’s useful to think of Si as an internal algorithm to find and determine what things feel pleasurable to you.
Let’s imagine you want to take a bubble bath and you don’t know yet which temperature will feel ideal.A strong Si-user (xSxJs) has perfectly oiled Si-valves, slowly adding a bit more warm or cold water, testing things out carefully step by step until they find the perfect temperature.With weak Si (xNxPs) on the other hand the Si-valves are rusty and it’s impossible to turn them this carefully. You have to use force and everytime you only want it to get a little bit warmer you turn it too far and steaming hot water comes out instead. So if you want to get the perfect average temperature you have to switch between the two extremes; freezingly cold and extremely hot.
Before an xNFP starts to actively develop their Si they turn those valves only rarely. They don’t actively look for experiences, staying mostly in the background, often appearing awkward and/or bland. But once they get into active Si-development they turn their Si-valves more often and as a result will also try out and experience more extreme things in their life.
So if an xNFP wants to learn what kind of relationship feels right to them they will often try out and switch between relationship-extremes: ultra-loyal clingyness, switching with a few months/years of whoring around, until they finally will set down for something in between.
