Sex with friends' sisters. Acceptable?

[HopeydaFish]

[ QUOTE ]
[ QUOTE ]
A friend of mine banged his best friend's sister for 3 years without the best friend finding out about it. He was quite convinced that his sister hated the guy in question, and was never suspicious. It's been 10+ years since this all went down, and he's still none the wiser.

[/ QUOTE ]
Yes, this is pretty much the exact situation I describe above. What is my play?

[/ QUOTE ]

It depends on all sorts of factors:

1) How much do you want to stay friends with these people?
2) Will broaching the subject potentially end any friendships?
3) Does the guy who banged the sister have any "secrets" that he knows about you that he could spill in retaliation?
4) Is it possible that your friend will "shoot the messenger" in that he'll blame you for not telling him about the banging sooner?
5) Do you have any animosity towards the guy who banged the sister?

In my case, I never told my friend that the guy was banging his sister because I knew that my friend would have been upset with me for keeping the information from him for so long. I also knew that this information would devastate my friend and would hurt his relationship with his sister. Finally, the guy who banged the sister had some dirt on me and I knew that he'd find a way to retaliate.

In the end, I decided that staying out of it was the best solution. Telling my friend that his little sister was getting [censored] regularly by his best friend would have caused a massive [censored]-storm that I would have been the centre of. I didn't need the drama in my life.