Originally Posted by Jinn

There's someone else takes the most guts to say, and is the most appropriate answer in this situation, because it's the most true. If someone told me it wasn't working out, I'd want to make it work out. If someone told me they weren't happy anymore, I'd want to make them happier. Both of these rely on the fact that she's willing to work with me to "make it work" and "make her happier."

What you're talking about, however, isn't that. You're not happy and it's not working out, but more importantly you don't want to work on it because you've found someone else. That's what they need to hear, not give them the false hope that they can rectify the situation.