halacha - "man seduces a woman for the sake of marriage"

Rambam isurai bia 21:13 (Chabad , sefaria , Hebrewbooks , mechon-mamre)

Whenever...a man seduces a woman for the sake of marriage...all of the children born in these situations will be rebellious and sinful. (Chabad translation)

Is this true that that a man should not seduce a woman for the sake of marriage?

1. Are there groups of Jews careful with this?


2. Do later rabbis bring this law?


3. What is the source of this law?


4. What is the definition of seduce in this case does it include persuasion (warning YouTube link)?
   
   If not, is persuasion permitted/preferred/ avoided?

Sources on subject will be greatly appreciated