In the book you see a detailed description of your girlfriend. There are stats like height and weight. Her personality and history is described, including her relationship to you.
You look at her age, 21, a few years younger than you are. You get an idea about what to rewrite, her age, and see an older version of your girlfriend, maybe one that could fullfill your MILF fantasies.
You use a pencil to write her new age of 38. You figure that's a good middle ground where she's considerably older than you, but not too old. After a moment, you see the book's text shimmer. Her other stats have also shifted to accomodate her new age. Like, her occupation is no longer 'student', but now she's an office worker in a marketing department. You check her relationships and see that she's still dating you.
You're not done yet however. Looking at your girlfriend's stats, there's a few things missing to make her a proper MILF. Her physical stats are mostly the same, only a few lbs heavier. Her bust as meager as always. She's still pretty petite. You can change that. You rewrite her stats, upping her bust from an B cup to an F cup. You also had a few inches of circumference to her hips. You see the lbs number increase as you've edited her to become much curvier.
For the final touch, you want to add the 'Mother' in 'mother I'd like to fuck'. You open her page of personal relationships. She's got no kids, but that's about to change. You write in that she's got a daughter, a 18 year old daughter. You smile at the thought that you will be closer in age with her new daughter than your girlfriend herself.
You decide you're satisfied for now, and close the book. It's time to see your new girlfriend in person instead of just reading her stats.
You had already planned to visit your girlfriend today. You pull up your phone and check your message history with her, and it seemed to still be the case that she'd invited you over. Now it wouldn't be to her small dorm, but to her own house with her being an established working proffessional.
You travel to her home. Once there at the door, you ring the doorbell.
The door opens, and you see what for a few second you shortly register as your girlfriend, but then you realize who this is. She's similar, but also different, younger-looking, slightly lighter hair, and much bustier.
"Oh, it's you," she glares at you, then she turns around and yells, "Mom, it's your boyfriend!"
She then walks away. You take note of her sizable rear. You hadn't designed your girlfriend's daughter in any manner, but it seems like your girlfriend's new curviness made her spawn a daughter with a similar disposition.
"I'm coming," you hear a familiar voice shout.
There she arrived, your girlfriend. You could see she was older, her skin was a tell in how it lacked a youthful luster. A few lines on her face. Overall, she didn't look too old, or even that different, well that probably would have been the case if you hadn't changed her further. The enlarged chest you'd given her was large, and very noticeable with how she was showing so much cleveage, your eyes drawn to all the pale skin and volume at display.
She grabbed your arm. "She's about to leave, so you don't have to worry. Soon, it'll just be us two."
"Okay." You nod.
She aggressively pulls you down for a kiss, and you oblige. You smooch her, and grab her behind during, now there being more to grab on. She's so soft now. You kiss further.
You're interrupted by an annoyed voice. "Bye! I am leaving!" your girlfriend's daughter announces as she exits.
Your girlfriend rolls her eyes then chuckles. "Kids. She still hasn't accepted it. I hope you don't take it personally. It's always awkward for a child to see their parent date." She pauses. "Of course you being so young doesn't help." She giggles.
She walks her fingers up your chest. "Now where were we?"