I too have experienced big, unrecoverable losses: several were caused by manipulative people thinking NVC or similar allowed them to force resolutions to their misconduct by manipulating others’ emotions, while never engaging in direct discussion.
Many of these discussion frameworks are most often used by toxic and manipulative people, so they become associated with that behavior — though the framework itself is neutral to good.
This would work better if both parties practiced NVC, as they may reply with what your comment made them feel and that would help clarify the confusion. But it's going to be hard to find that type of situation given that NVC is not quite that widespread, so the NVC happening on only one side of the conversation truly make it difficult.
So we have to either be very careful with our wording and be aware of all possible misinterpretations, to make sure our wording only says what we want it to say, and/or we have to keep clarifying ourselves until our true meaning is clear and confirm with others what they've understood, which can be awkward. No wonder NVC is hard.