The Maitreyi-Yajnavalkya dialogue includes a discussion of love and the essence of whom one loves, suggesting that love is a connection of the soul and the universal self (related to an individual):
Lo, verily, not for love of a husband is a husband dear, but for the love of the soul a husband is dear.
Not for the love of the wife is a wife dear, but for love of the soul a wife is dear.
— Brihadaranyaka Upanishad 2.4.2–4
Variant translation:
Truly, it is not due to the love of a husband
that a husband becomes dear,
but due to the love of God
that a husband becomes dear.
Truly, it is not due to the love of a wife
that a wife becomes dear,
but due to the love of God
that a wife becomes dear.
Truly, it is not due to the love of all things
that all things become dear,
but due to the love of God
that all things become dear.