וַתִּדְבַּ֣ק נַפְשׁ֔וֹ בְּדִינָ֖ה בַּֽת־יַעֲקֹ֑ב וַיֶּֽאֱהַב֙ אֶת־הַֽנַּעֲרָ֔ וַיְדַבֵּ֖ר עַל־לֵ֥ב הַֽנַּעֲרָֽ׃
און זײַן זעל האָט זיך באַהעפֿט אָן יעקבס טאָכטער דינהן, און ער האָט ליב געקריגן די מײדל, און ער האָט גערעדט צום האַרצן פֿון דער מײדל.
Rashi
על לב הנערה [AND SPAKE] LOVINGLY TO THE DAMSEL (literally, he spoke to the heart of the maiden) words that would appeal to her heart: See how much money your father has lavished for a small plot of field. I will marry you and you will then possess the city and all its fields (Genesis Rabbah 80:7).
Sforno
ותדבק נפשו, this was the opposite of Amnon having raped Tamar whose infatuation with her turned to disgust the moment he had satisfied his biological urge. (Samuel II 13,14-16)
Radak
ותדבק נפשו בדינה בת יעקב, his soul felt a strong attachment to her on account of her beauty as well as on account of the fact that she was the daughter of an outstanding personality, Yaakov.