You're a degenerate and have overexposure to pornography which rewires the brain to associate seeing a penis with seeing said penis inside a woman which makes you sexually confused and in that confusion begin to mistake it for a fetish or some form of sexual identity but you don't wish to embrace that fully because you know in your heart you weren't born like that you're just a sick fuck who fell victim to sicker jewish fucks (porn producers) with no willpower and because you have no willpower instead of rejecting the notion of having unconventional sexual desires entirely and ceasing pornographic exposure and maybe getting laid by a real woman you latch onto something less offensive to your current sensibilities which is to say fictional women with penises and in doing so self insert yourself in a way because 1. you know what it's like to he aroused and 2. you know what it's like to be aroused by the female form so the female form having an erection is the ultimate gynephiliac fantasy for someone as lost as you