CYOTF - Transform your girlfriend

You are an ordinary guy who lives with your lovely girlfriend in the same house, both of you lived happily and sometimes have an erotic together. Your girlfriend is quite a lovely and wonderful girl who you love very much, you are happy to be with her. One day, while you and you are on the bed after you both have sex, you thought about something interesting that makes a strange, weird, and yet erotic that you and your girlfriend would love to have fun with each other. Though you don't cheat on your girlfriend because you love her so much, you just want to try something else that wouldn't cheat on her. Then, something pops into your head as you have an idea, why not transform your girlfriend without cheating on her so that you both could still have an erotic romance?

With that, you jump out of bed while your girlfriend rests and then you try to figure out how you're going to change her. After that, you got an idea.