Ladies, how did you decide to try fisting? Yourself or by another person?

No matter what I do, I get to the point of almost getting that 4th finger completely in my wife’s pussy, and she automatically freaks out asking how many fingers I’m using on her. Tell her 4 and she gets all pissed off. But her screaming, legs shaking and dripping pussy tell me I’m doing all the right things. Not sure if that number triggers a whore mentality or what but no matter how much I reassure her that it’s all good she acts like I did something wrong