How exactly did Yakov 'steal the heart' of Lavan?
Targum Onkelos and Targum Yonasan: By simply not informing him of his plan to run away. Ohr ha'Chayim
How could Yakov leave his host of twenty years without saying 'goodbye'?
Seforno: He did not do this out of ill-manners, but because he was afraid that Lavan, with the help of the people of the town, would steal from him. 1
Ha'Emek Davar: Hashem did not promise to protect him from Lavan, and it was not easy to remain on the road a long time without Lavan finding out. He hoped that Lavan would not find out for a while, but Hashem arranged otherwise. In any case, he saved him. 2
Why does our Pasuk refer to Lavan as "Lavan ha'Arami"?
Ramban (24): To teach us that, despite the fact that Lavan was a sorcerer who divines with Terafim, Yakov succeeded in 'stealing his heart'. 1
Seforno: To explain why Yakov stole Lavan's heart (Refer to 31:20:1:1). Because, had Lavan realized that Yakov was aware of his feelings, he would have placed obstacles in his path to prevent him from leaving.
Ha'Emek Davar: Even though Lavan was a master trickster, Yakov succeeded in 'stealing his heart'.
How could Yakov have informed Lavan that he was fleeing?
Targum Onkelos and Targum Yonasan: "Bore'ach" means (not that he was 'fleeing' but) that he was 'leaving in haste'.
Oznayim la'Torah: The Pasuk means that Yakov did not inform Lavan (not that that he was fleeing, but) because he was fleeing'. 1