Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: For a little bit of the backstory, this guy and his gf have been together for roughly 2 1/2 years. About a year ago, I reached out to my friend to tell him that she was cheating on him, and should do something about it. He felt conflicted because the only proof I had at the time was just some of the first hand accounts where she’s dancing with other guys or she’s being flirty when he’s not around. They are long distance, and when we go out to bars, I constantly find her in situations where she’s dancing with other dudes. Fast forward, they’re still together, and now I have some more proof where i have personally heard her say she’s made out with other dudes/ wants to fuck one of her co-workers. 

The reason I haven’t told him lately is because I’m afraid he won’t do anything, plus she is best friends with my gf as well and I am afraid of effecting their relationship. 

not telling my best friend his GF is continuing to cheat on him