Is what the questioner did—attempting to convince a girl against her fiancé before the marriage is finalized, believing her claims about his bad character, and that she agreed to him out of obedience to her family—considered incitement (takhbib) of the wife against her husband?

You did well to end your relationship with this girl, and we ask Allah to forgive what has passed and to grant you success in the future. Your silence regarding her statement that she would convince her family to annul her marriage so she could marry you, and your attempts to reconcile her with her husband, were perceived as instigating her against her husband. You should have unequivocally denied any intention of marrying her, and it was obligatory to stay away from her, as many marriages based on "alleged love" fail.

Allah Almighty says: {But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah Knows, while you know not.} [Al-Baqarah:216].

The figures you mentioned at the end of your question have no bearing on the fatwa we have given you. When you intend to marry a woman, it is sufficient for you to inquire about her religious devotion and character from trustworthy people. If they praise her, you should see her with a lawful gaze, and seek Allah’s guidance (perform Istikhara) regarding her matter. If your marriage to her is good, Allah will facilitate it for you.