SB 9.18.20-21

taṁ vīram āhauśanasī
 prema-nirbharayā girā
rājaṁs tvayā gṛhīto me
 pāṇiḥ para-purañjaya
hasta-grāho ’paro mā bhūd
 gṛhītāyās tvayā hi me
eṣa īśa-kṛto vīra
 sambandho nau na pauruṣaḥ
tam — unto him; vīram — Yayāti; āha — said; auśanasī — the daughter of Uśanā Kavi, Śukrācārya; prema-nirbharayā — saturated with love and kindness; girā — by such words; rājan — O King; tvayā — by you; gṛhītaḥ — accepted; me — my; pāṇiḥ — hand; para-purañjaya — the conqueror of the kingdoms of others; hasta-grāhaḥ — he who accepted my hand; aparaḥ — another; — may not; bhūt — become; gṛhītāyāḥ — accepted; tvayā — by you; hi — indeed; me — of me; eṣaḥ — this; īśa-kṛtaḥ — arranged by providence; vīra — O great hero; sambandhaḥ — relationship; nau — our; na — not; pauruṣaḥ — anything man-made.
With words saturated with love and affection, Devayānī said to King Yayāti: O great hero, O King, conqueror of the cities of your enemies, by accepting my hand you have accepted me as your married wife. Let me not be touched by others, for our relationship as husband and wife has been made possible by providence, not by any human being.

While taking Devayānī out of the well, King Yayāti must certainly have appreciated her youthful beauty, and therefore he might have asked her which caste she belonged to. Thus Devayānī would have immediately replied, “We are already married because you have accepted my hand.” Uniting the hands of the bride and bridegroom is a system perpetually existing in all societies. Therefore, as soon as Yayāti accepted Devayānī’s hand, they could be regarded as married. Because Devayānī was enamored with the hero Yayāti, she requested him not to change his mind and let another come to marry her.