וַתִּדְבַּ֣ק נַפְשׁ֔וֹ בְּדִינָ֖ה בַּֽת־יַעֲקֹ֑ב וַיֶּֽאֱהַב֙ אֶת־הַֽנַּעֲרָ֔ וַיְדַבֵּ֖ר עַל־לֵ֥ב הַֽנַּעֲרָֽ׃
И душа его прилепилась к Дине, дочери Иакова, и он полюбил девицу и с утешением говорил девице.
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.