11 Answers

I don’t hit. I’d probably make my feelings known and leave it at that. Steam alone……...

No, I don't give black eyes.  She will then run to his defense anyway. You probably can't make someone do what YOU think is best for them. 

Of course I wouldn't.  Here's a tough thing to consider, though.  
My son spent nearly 6 years with the loser who is the mother of his three children. I couldn't understand why he was so hung up with this person; she beat on him, nearly cut off his ear with a garden hoe, used drugs, was destructive of his property (still is), is an alcoholic, ignorant, just "not a nice person" in general (which is what a classmate of hers told me five years ago). What on earth was my son doing with such a low life example of humanity?  (Icing on the cake is her parents, abusive, domineering mother, alcoholic father)
It dawned on me one day, and has bothered me since, that if my son were so attracted to someone I considered a "loser", what does that make my son?  I'm sure HER parents thought my son was a "loser"... 
Let your sister know how you feel, POLITELY, and be ready to pick up the pieces when the relationship disintegrates.  

I have witnessed this with my adult sister. Not much anyone can do when she is head over heels in love. Her choice, her life.

As for black eyes, as long as she doesn't get one, I can't see any punches getting thrown from me.

My sister married one.(And yes...I did).

Tough one terrey,you could be done for commom assualt,just fill his hat with crap ram it on hes head,and kick him up the bum,not to hard though,

It depends upon how big he is and if he can fight. If I don't consider this to be an option, giving my sister one would be a possibility, but only if I kept her in my dungeon for awhile and she refused to waiver.

You can try to help by expressing some advise, however, it is usually not taken.  That's about all one can do. 

Keep your hands to yourself. Using fists will lead to more problems. Your sisters affairs are her own, not yours. 

Terry, you can't do anything about it except talk to her and I'm sure you have. She'll probably just keep on doing her own thing untill she reaches the breaking point. She's lucky to have a bro like you who cares about her.