What is meant by sirr in "do not promise them secretly"?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1.The term sirr ("secret") here refers to marital intimacy. This has been reported from Ibn ʿAbbās. The meaning, therefore, is: do not offer them that explicitly while they are still in their waiting period, "Except that you speak honourable words", meaning: in which you say nothing that that is indecent or explicit in this regard.

1. "Promising in secret" means saying to her, "I am in love with you. Promise me that you will not marry anyone else." This is another view reported from Ibn ʿAbbās.
2. The term "secret" is interpreted as referring to fornication [al-Ḥasan, Jābir ibn Zayd, Abū Mijliz, Ibrāhīm, Qatādah, al-Ḍaḥḥāk]
3. The meaning is: do not marry them secretly during their waiting period, making it public later only when they have become lawful to marry. [Ibn Zayd]