[Kyle]

yes there are many times when a 3rd person should interfere such as when something gets violent or harmful in any way to either of the people also it is mostly a judgment call, i my self interfere alot, i am a teen consular(a teenage version of a guidance consular to give the best advice or to just listen and be there to hear problems 24-7 i also sometimes act a personal suicide hotline but i try to forward those calls to pro's) and that is something i do when you interfere it doesn't have to be to break up anything but to just drop hints or have a small talk about the problem in private. But don't take this that you should always do something because it isn't some thing that u like there have been many times where i hate some of the things people tell me about and i want to do what i can to help but cant. there have been times where interference from a 3rd person has saved lives so yes if the 3rd person uses there judgment and knows something about the situation should do something even if it is just writing an unsigned letter.
for any info on teen consulars go to your local branch of the YMCA YWCA or teen center