If I see someone I care about doing something I know isn't good for them then I should do the right thing and confront them about it even if it hurts them emotionally.

Yeah, well... some of your statements are more problematic than others. ;)

For instance, my friend is taking drugs or is in an abusive relationship or even something less obvious like my friend is scared of marriage and is about to break off a relationship with someone they are in love with because they're scared. Should I ignore these mistakes or should I be a friend and talk to them about it even if I know they won't want to face these problems and it could even damage our friendship?

Speaking your honest opinion is never "hurting someone." "Confronting them about it" can be.

The major difference is in whether people are made to "go away" to be a puppet for others. Someone who tries to convince you that having an honest belief is "hurting them" is hurting you. Someone who "confronts someone" into having the beliefs that they themselves have rather than the beliefs that the person originally had is hurting them.

Neither is entirely prudent. 'n incidentally, beef contains the controlled substance GHB, the common spice sage is a narcotic, and the like, so you may want to clarify your philosophy on "taking drugs."

Back to the story, however - are you trying to make someone "go away" and conform to what you want instead, or are you just giving your honest insight - and dropping it? There's a world of ethical (and mathematical) difference.

Just as a side-topic, have you tried listening? Your marriage-averse example could be undergoing a vast and complex personal experience which you appear to be disregarding in your rush to "tell" them - sometimes, listening can do more.

As an anecdote, a young girl of whom I have legal custody briefly had a boyfriend who exhibited most of the domestic-violence warning signs; when she dropped to the level of "he's so sexy because he got in a fight," I... sort of mentioned something about it.

She basically ignored me... and that was okay. A year or so later, when the community was on alert because her ex-boyfriend was trying to hunt down her current boyfriend (armed, I believe) for violence, I kept my "I told you so"'s to a minimum - it seemed polite.

Speaking my honest opinion without trying to coerce or devalue anyone - namely, her - gave her one point of view to consider. Trying to tell her what to do would have given her no one to talk to, and... left her isolated with a person who fit every checklist item on a domestic violence pamphlet.

Which is love - listening to the person as they are, or ordering a person to pretend to be as you would want them to be?

Lemme know. :)