Health:
I was addressing issues related to the entry into marriage. Not the issues that occur within it, and when others interfere when the going gets rough. Your point is valid, but it was not overlooked. It was just outside the scope of my comment.
You are correct that the interference factor is severe. It might meet the criteria for shmiras halashon violations, and might sometimes not. Try this example. A couple is married, with the most wonderful information having been traded about the two prospects. Little known, was that the young man had been in psychiatric treatment for 2 years, was taking medication for a rather serious problem, and that this is a condition that is not curable, but treatable with meds to reduce symptoms. When the young bride caught her husband taking a pill, he told her it was a vitamin. It was many months later when the truth was revealed. All the while, he was “going to kollel”, where his father was his chavrusa, as he was not material for anyone else. No lashon horah, no rechilus, no motzi shem rah. Just lies that even the Chofetz Chaim instructs not to say.