Yes, you postpone.

You beg and plead with your sister, but she explains to you that you are simply not ready for it, and that these additional days in chastity are necessary. She just saves you from embarrassment.

You understand, and when the day comes, you tell your GF that you are sick, and they have to postpone the anniversary until you are healthy again. She is sad and disappointed, but she believes you.

You feel bad. Not only because you postponed the date, but also because of what happened in the last session. Somehow, among all that jerking off, pussy juice and an actual blow job, it was that final kiss on your lips, that felt the most like cheating on your girlfriend. You keep on thinking about it.

After excruciating 7 days in the chastity belt, you finally sit in your sisters room, ready to be released, ready for what she calls “Your final task.”

She unlocks you, and her finger just glancing your dick already gives a feeling of electricity through your body.

Your sister says: “Ok brother, you got used to the warmth and wetness in the last sessions. You are almost ready to feel the inside of your girlfriends pussy. Just one more thing you need to get used to..”

While saying that, she slides down her pants, revealing her perfect, smooth legs. Your mouth drops open and you are instantly hard..

Sister: “Nono..not like that. Of course you cant be inside me, Im your sister.”

You understand, but are visibly confused.

She lines down on her bed and says: “We gonna practice what you will do with your girlfriend, all until the moment of penetration of course. I will stimulate you with my hand. If you lived through that moment before the penetration already, you will be much more relaxed when the time comes. And the same time of course, you have to try not to cum. This time its really 10 minutes. For every minute that you come too early…you know the game.”

It makes sense to you. And you are incredibly exited. Your sister has a similar body as your girlfriend. Your sister is just a little bit shorter, her legs are surprisingly long though, and her tits are a little bit smaller, but much perkier and still a good hand full.

She tells you: “Take off my panties.”

You do, you put your hands on her hips, you grab her little panties with your fingers and slowly pull them down, strife them over her ankles, and put them on the bed. Your sisters naked legs, her smooth shaved pussy, her ass, her flat tummy, they are all there in front of you. She looks up at you. You think about how much you would love to spread that legs and penetrate her. Thats when she says: “Spread my legs.”

You do as she says, the skin on her thighs is so soft.. She tells you: “This is it, you fully have to envision this moment. The penetration. I want you to get really close to me, around one foot away from my pussy with your dick. You will, under no circumstances penetrate me of course. But I want you to imagine it.”

Her hand touches your dick. So good…. She starts to slowly stroke you, while making you say how you are about to penetrate her. She tells you to envision the worst case, to tell her how you about to penetrate her, but you will cum the moment you are inside of her…You get closer and closer to her pussy, and she tells you, the moment you get inside, you have to cum for her…you get closer, just one inch away from her beautiful pussy, she jerks your dick… it would be so easy to penetrate her.. she keeps on saying how the moment you penetrate you will cum, you will fill her up…you will…

In that moment, the tip of your dick touches the entrance of her pussy, your dick twitches hard, you moan uncontrollably, and you are cuming all over your sisters belly and thighs. The moment you start to spurt, she starts screaming: “Oh my god! You are cuming! Already! You didnt even penetrate me and you are already cuming! What a loser! What a premature loser that cant hold his cum back! I knew you wouldnt last with me! HAHAHA!”. While hearing these sadistic, hurtful insides, you are still uncontrollably jizzing all over her body. The you collapse onto her, while she is still laughing.

After a few minutes your breathing and heart rate start to normalize, and your sister stopped laughing.

Sister: “You know why I was so harsh with you now? Because I want to connect cuming to early with something bad, with humiliation and embarrassment. Only then your brain will stop you from doing it. Believe me, it will work.”

You: “But will I be ready at the anniversary?

Sister: “Yes. Even though that was really fast…less than 1 minute to be exact…I now believe that you will be ready in 10 days. But we have to use these last 10 days well. Of course, like promised, you will have to wear your chastity belt the whole time, so we need to focus on mental exercises. Every day, when you get horny, you have to focus on what you just experienced. Visualize this memory, of coming closer to my pussy, about to penetrate it, prematurely ejaculating for me, and the humiliation you felt when I laughed about it. I need you to focus on that, every day, every time you get horny. Then I’m absolutely sure, when the 10 days are over, it is not going to happen to you.