Now what, exactly, does that mean? What does a woman really mean when they say "you're too nice..." or "you're too good..." (for them)?

Does it mean you're not exciting enough for them, that you're too "safe" and lack some semblance of "danger"? Does it mean they have such low self-esteem that they actually think you can do better than them? Does it mean "I'm too nice to say fuck off"?