A - How do you know they are narcissist?
B - Why do you assume that the friend doesn't already know?
C - Why do you think they might want to know?
D - Is it any of your concern?
If you can satisfactorily (and honestly) answer those questions then yes, tell the friend, otherwise leave the matter lie.
If you were really her best friend then you shouldn't say anything. they shouldn't have to worry about a competition. because most likely they will tell the partner and you don't want to take chances of them having a thing about you. that will be all bad. not to mention you don't need to put stress on their mind. she/he is your best friend. you don't need to lose a friendship over a partner...
Yes. Otherwise they'll get deeper and deeper into it. At lease they have a fighting chance if you tell them.
du it urself
You tell their partner? And here's also a tip, Tell ur friend to tell the other partner who doesn't know to have a HIV test with hiim to make sure everythings ok... BUSTED.
you flirt with the person your friends dating and try to hang out with your friend and their partner or just the partner. Get to know the person better and maybe go to the movies or dinner (don't tell your friend of course) and maybe after a while you've been doing that ask the person if they like you or not. If yes, then try going out on a DATE with them and they will break up with your friend. If no, then tell your friend that you went on dates with them and say your friend's partner gave you roses (buy roses and say they were sent to you from the partner) and chocolates and other stuff and then your friend will end up breaking up with the partner then you can go out with the partner.
i would tell him right away ...
Tell him to go and leave you alone.
Please NO!
tell my friend sorry and tell the truth
Tell your friend to stop bothering you or tell an adult
you should propably tell you best friend that is a girl she can help.
Be careful if you do, the narcissist can be a monster to anyone who hurts their pride.