Hmmmm. You're saying PUA's have morals? I want some of what you're smokin'!
OK, in all seriousness, PUA morals are something that has
never been formally defined. There are so many artists and so many styles and schools of seduction in the community that they all disagree on SOMETHING.
However, MY particular "Pickup Morals" are based on a few simple ideas:
"Leave her better than you found her" - Ross Jeffries
"I don't 'steal' a man's girl. She came of her own accord. Indeed, he GAVE her to me. Women are gifts men give to other men" - Zan Perrion
"You can't force the willing."
"Never kiss and tell."
"Enjoy their fruits, but neither break their heart nor give away yours."
"I believe that man DOUBLES his existence when he devises any means of multiplying his pleasures" - Casanova
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Now there are some "players" (not real PUAs) who do horrible shit like telling everyone who they slept with, stealing their neighbor's wife (just watch "Jingle all the way" this Christmas to get an idea of what these AFC "players" try to pull off). They also treat women like shit, use sex as a weapon, push her to leave her boyfriend/fiancee/husband etc. Don't fall into that trap. These guys get lousy sex from low-value women. And they are total scum.
LONG STORY SHORT, I believe you shouldn't break up couples. EVER. If they are truly happy with each other (which is RARE) leave them alone or better yet, make friends with them - the girl could introduce you to HER single friends.
But if there is the slightest possibility that her boyfriend is NOT satisfying her, or she feels no attraction to him anymore, then by all means
RELIEVE her of her misery and let her feel what a real LOVER is truly like. Even so, I am still AGAINST breaking up their relationship or asking her to leave him.
Let her keep the boyfriend.
You are her secret lover, and you get more pu**y than he ever will.
Most women will cheat on their partner and withhold sex from him simply because he is boring or needy. It's not their fault - they are NOT sluts, they just crave adventure and their man bores the hell out of them by placing them on a pedestal. They NEED you, fellow seducers.

There are two kinds of men in the world - the LOVER (who 'gets some' without giving much) and the PROVIDER (who gives everything and gets nothing).
Which one are you?