Yes, you slowly penetrate her.

You can’t wait any longer! You do it! You push your dick inside of her. Your tip slowly enters, like you kept on visualizing…and you feel that warmth and wetness that you obsessed about the last weeks! You are not even half way in that a feeling overwhelms you! NO! NOWAY! You are not about to cum prematurely now! Focus! Control yourself! Just be a man and continue!

You push your dick further, the feeling of wanting to cum is almost unbearable, and you barely hold on…why?…why is it so difficult? Why Are you about to cum prematurely?…at that moment, when you are almost completely inside your girlfriend for the first time, the waves on pleasure in your body, pair with flashes of your training these last weeks and with one brutal realization:

Your sister didnt train you to last longer, she trained you to become a premature ejaculator!

You look up towards the door, while pushing the last inch of your dick inside, and you see your sister, still standing in the door, her right hand still in her pants, her left hand now squeezing her bare tit! Her perfect tits, that you see for the first time since she entered puberty. Her face full of lust and anticipation, biting her lip, looking straight into your eyes. This beautiful, perfect view, combined with the feeling on your dick and the humiliating realization send you over the edge. You start to moan, to spasm, your dick slips out, after just one little pathetic entering..not even performing one single thrust, and your cum splashes all over your girlfriends belly..

You realize that this is it, the moment your sister trained you for, the one you kept on visualizing, the moment of humiliation and ultimate embarrassment. While your whole body shakes and you moan loudly, almost screaming in pleasure, you only try to keep your eyes open, gaining another glance at your sister. At her perfect boobs. At her face.. How does she look like now? Now that she got everything she wanted….Now that she fulfilled her fetish fantasy.. No that she completely and successfully humiliated you?

You see your girlfriend looking in absolute shock, saying; “Youre kidding me right?”. You look past that and see your sisters face, looking at you one last time before disappearing behind the door. Your cute, little, younger sister. You see her face, her eyes looking right into your soul and you feel….total humiliation. She got exactly what she wanted. She feels no remorse. And she will tease you about it forever.

You collapse onto your still shocked, disappointed, unsatisfied (now mostlikely ex-) girlfriend. She will tell everyone about it, you know it.

And then one fact becomes crystal clear: This feeling is not transient. Its permanent. Your sister rewired your brain completely. She messed up your sexuality in ways you will probably never be able to fix. She turned you into a premature ejaculator. And you will have a premature ejaculation problem for the rest of your life…