Don't get me wrong...I don't want to give sb a sermon but rather hear some opinions on that issue because I haven't yet established one by myself....
(In fact, I denied sex once due to that and I don't know if I should regret it. )

Is it "ethical" to fuck a HB if she has a boyfriend?

Isn't it kind of disrespectful? On the other hand cheating is her decision not mine. If someone would fuck my girlfriend (if I had one) I would never be mad on the guy who fucked her. However, if she tells me she has a boyfriend and I continue the game, I become partly responsible, I guess? I'm new here so moreover I don't know if the phrase "I have a boyfriend" might be a void shit-test.
And if I do it, how can I avoid judgements (especially on her). Or assume you would meet a guy who knows you banged his girlfriend. What would you tell him?

Just tell me what you think

I assume you mean "if" she has a boyfriend, not "in case" she has a boyfriend.

The answer to which, is: no.

Really? So you'd encourage other guys to fire inbetween the legs of your girl if you had one? Even though it doesn't change things you'd surely want to kick the fuck out of him if you ever saw him?

He's not really the kinda guy your going to go get pissed with and exchange high fives on a Saturday afternoon or go to the football with is he?

I'd say it's a bad call for a couple of reasons.

Mostly it stems for a lack of personal standards. A girl being willing to sleep with other people and lie to their boyfriend points to some pretty serious character flaws on her side. You shouldn't really want someone like that in your life even on a superficial level.

Personally I'd be more concerned about the guy. When I was out doing the whole pickup/player thing a major rule I tried to go by was the whole Hippocratic oath thing of 'above all, do no harm'. i.e. getting laid should not come at the expense of hurting people, physically or emotionally if at all possible. So the girl might be totally fine with the situation, but by getting involved you're becoming complicit in something that can potentially cause a lot of emotional harm to someone you don't know from adam who never did a thing wrong to you. If she wants to cheat on her boyfriend fine, but she'll have to find some other asshole to do it with, not me.

I've heard people twist this to 'Yeah, but that's her business. You're not his friend, you don't have any obligation to him', but that just strikes me as a cop out rationalisation. People who think like that are assholes though in my opinion. The idea that you don't have to pay any regard to the feelings of people you don't know just so you can fuck some girl is repugnant, and you should see that as beneath you.

This is an interesting topic.

I wonder if some of the guys on this thread are being subjective with the matter due to having girlfriends currently.

I think the question asked was pretty generic so perhaps explains the replies so far.
Life is never generic and simple though.

So as I have no girlfriend (and not done for a while, see my friend report),
I feel it's my duty to plays devil's advocate.

A lot of girls I speak to will turn around and say they have a boyfriend. When that happens I typically try and gauge how serious I think she is. If it 'feels' serious to me I would not pursue her. However there are a lot of gray areas.

What is a boyfriend ?
According to wiki (foundation of all knowledge):

A person's regular male companion with whom they have a romantic or sexual relationship.

Someone who has been termed a 'boyfriend' might not necessarily feel a romantic connection to their 'girlfriend'. They could be a 'fuck buddy'?!

If the OP had replaced the word boyfriend with fuck-buddy would have the responses been different ?

This is all quite subjective.
For myself I think I have to apply some level of intuition and human intelligence for each girl I meet.
However I am not a mind-reader & my intuition is not perfect (I'm still learning women..)

One girl I have been in contact with did mention a boyfriend. However this was a good while after our first date. They could have met after or before, I did not feel a need to ask more. If we do meet again, I will assume that relationship has ended or it was not serious. I will not specially ask about it, unless it feels like I should.

She or any girl for that matter could turn around after you've had sex with them and say 'oh by the way I'm married / have a boyfriend'

If that happened to me I would not see her again (of course) - I agree with not wanting to intentionally hurt other peoples feelings. However it could happen due to girls being bad eggs.

Ultimately you can only take responsibility for what you know about not what you don't.
So I am agreeing with what the others are saying, taking the meaning of boyfriend as 'serious sexual relationship' but I am saying there could be shades of grey worth exploring.

Thank you all for your answers, helped me a lot :-)! I understand it's a very emotional topic and it might hurt a lot if you know how it feels being cheated on, but let's face the pain you feel when your girlfriend betrays you: it's simply abused trust not the sexual interaction itself...And a stable person should be principally able to subordinate temptation to personal values. So you could see the guy as a person who has revealed a lack of integrity which is not acceptable in any way (ok, I know few will think this way actually but it's a theoretical point of view ). So if you say:

I say: It depends....he surely wouldn't become my friend but if I really don't know him, I would mainly blame the girl and be happy of becoming aware of her serious character flaws. In the end, temptation is everywhere (eating the pizza without your flatmate, selling acid to your grandma, adding a moustache to the Mona Lisa in Paris...) but the decision is up to you.

Nevertheless, I think Stein makes a good point here: Sure, a relationship where the girl is cheating has to have problems in some way but if you seduce her (aware of the fact that she has a boyfriend), it's you being the catalyst for pain and anger. I personally think the purpose of pickup should be enriching the world with positivity. it's not only more ethical but it helps you to establish a proper inner game. (ok these sentences were really gay - but they're true)

Last I want to thank Markuk for his thoughtful answer :-) ... It's probably always most right to evaluate the specific situation. Unfortunately, I still have to get a good sense of intuition but experience will do its job.

Oh god...after this long and serious post I'm feeling like a hippie in the 60's...
You're awesome guys! And sorry for my bad english ;o)

U wot m8?

I would want to kick 10 layers of shite out of him. Obviously she would be getting slut shamed too like but the guy better stay out of my way for his own health & safety.

It would definitely depend how much I loved or cared for the girl but I'm going on the example of being head over heels in love with a drop dead gorgeous sex bomb. If it were some average bitch, probably not so much.

In fact I've experienced a similar-ish scenario, only much worse. Rather than go into it I'll just point out that I moved 50 miles away so that guys didn't end up dead & me end up in prison.

The point is, if you do this on someone you should be prepared to face the consequences. I'm still not 100% sure what might happen if certain guys cross my path. But the good thing for all involved, including me, is that I live far away.

Plus, karma & stuff.

No.

Elsewhere in life, yes you would definitely get that kind of knee jerk reaction but I think that on this forum it is more likely people have been on a journey and come to a considered opinion.

I understand the "shades of grey" argument and that attractive women often have orbiting men of some sort. To me though that's just the PUA world missing the point.

Sometimes I wonder if people have the social awareness to understand what a girl is feeling when she says "I have a boyfriend". It's either the simple truth, or it's a polite way of putting the brakes on an unwanted advance.

There are plenty of attractive women around, why not just respect people's resistance and chat to the people who actually like you in life? It's a whole lot easier!

If a woman uses the word 'boyfriend' does that automatically draw the conclusion that a) She is putting up resistance ? and / or b) she is in a loving sexual relationship and is not interested in meeting other men ?
(I'm not convinced)

I'm pretty sure we would all agree what women say can change one minute to the next and is often based on their current emotional state. Not always but more so than men.

Therefore whatever words leave her mouth cannot always be taken literally.
Even if she uses the word 'boyfriend'. Otherwise what other words are to be taken literally and which ones are not.

I would say most women who say 'I have a boyfriend' after I've first met them I would not persue. However sometimes I keep investing in them as I feel there is attraction and what she said was just a knee jerk reaction based on emotion not fact.

I remember one girl (Kerry - think I mentioned her in my Field reports) I dated who gave me her number even though she had a boyfriend and contacted me months later after they had split up.

Just need some now