You loved your boyfriend very much. You two had so much in common and he was so sweet and treated you really well. It was by far the healthiest, happiest relationship you had ever been in.

There was just one little problem.

Physically your boyfriend didn't live up to your fantasies. Now, admittedly, your kinks were a bit... novel, but you thought that even if he could move a little in that direction you'd be much more satisfied. Things would be basically perfect. It wasn't his fault he wasn't the sort of brute that turned you on most.

Then fate seemed to deliver a potential solution to you. A medical breakthrough could provide the solution you've been longing for. There's a medication that massively increases male virility and, the rumour is, can cause muscle and penis growth. You manage to get your hands on some and carefully begin dosing your beloved.

Things start off slowly, but soon enough the results are obvious. But they keep going and he becomes bigger and more "alpha male" as more testosterone surges through his body. You've debated stopping, that he has grown enough, but seeing him change excites you.

Though there is another concern. His sexual appetite is growing, and his more bull-like urges has made him attracted to women with big tits and good breeding hips. You can't bear the thought of your love leaving you for some bimbo... and you losing access to your new stud. Luckily the fertility medication has an equivalent in women. Just wait to see how excited he gets when you start to grow.

Thanks for reading my prompt. Basically, a couple gets caught up in a virtuous/vicious cycle of changes and give in to their base desires.

This is for an 18 RP. In terms of size, I would like to go very big for people, but not giant sizes. Cock size under two feet and breasts no bigger than watermelons. Happy to have lots of cum, milk, and very big pregnancies.

You can find my detailed kink and limits list on my DPP Profile. I'm looking for something long-term. Please send me a PM (no chat) with your ideas. I'm open to the sort of relationship between these characters. They can be a couple, friends, maybe something more taboo. Feel free to share your thoughts!