How about a different compromise?

You decide that you're definitely not bored with Erica yet, so you don't really want Amy right now, but you also don't want Craig to have Erica. However, he is your best friend—and you realize there is something you can do for him, while experimenting at the same time.

"Tell you what, Craig, don't pay any attention to Erica for now—what if I made some improvements to Amy?" you ask.

He turns his attention away from your nude cousin, as if he no longer even sees her in the room. "Sounds good, but I wonder what kind of improvements," he answers.

"Nothing too major," you assure him. "Let's see...Amy, what do you do for your bush?"

As per your earlier command, she doesn't get upset, but merely answers matter-of-factly, "I just trim it a bit myself."

"Okay, I want you to make a salon appointment at your earliest convenience to have yourself waxed," you command. "Pubes, legs, pits, the works. Make it a standing appointment."

"Oh, sure," she says, reaching in her purse to come up with her phone. "Let me set a reminder."

You look at her dark blonde hair that's just past her shoulders. "While you're at it, get your hair bleached platinum, and see what they can do about giving you a sexier look, even if they go shorter." With Erica being a brunette with long hair, you want Amy to contrast as much as possible, for potential future use. "And go for a manicure, where you get some long fake nails, and a spray tan."

Amy is still typing into her phone. "Ooh, I might have to take the day off work!"

Craig looks at you a little bit skeptically. "I don't know, man. This isn't quite—"

"No, it's great, Craig! Amy's going to be everything you want in a wife."

He blinks, and more enthusiastically, says, "Well, okay, then!"

You turn back to Amy. "You want to show yourself off in clothes that are as sexy and revealing as possible -- even at your job, you want to go as far as you can get away with. You only want to wear high-heeled shoes, too."

Amy looks down at her fairly conservative dress with its knee-length skirt, and her flat-soled sandals. "Oh, God, what am I wearing?" she practically moans. "I can't believe I walked out of the house like this. Can we do some shopping before brunch?"

"We'll go after brunch. You look fine for now," you reassure Amy. She visibly relaxes.

You continue with, "But you also always want to be wearing a lot of makeup, because you want to look sexy and slutty."

Only wearing just a bit of makeup, she seems nervous again, and goes into her purse. "I probably look like a pale freak, then! And I've only got some blush and a lipstick in here."

Erica speaks up. "I've got plenty of stuff in the bathroom. I can help you out."

"Oh, thank you!" exclaims Amy. She gets up and follows your nude cousin down the hall.

Craig's looking very confused, and you quickly realize why, saying to him, "You can pay attention to Erica again. That's who Amy just left with."

"Oh..." is all Craig says.