Why was Willy so harsh to Linda? Why did he treat her so meanly (must be based on some reasonable aspect of human behavior)

Willy's behavior toward Linda is, unfortunately, all too human. He wanted to be a great man, a successful man, a beloved father who has successful children. Linda becomes person upon whom he can take out his frustrations.

However, in life Willy has achieved only a modicum of success; he was never "great," and one of his children (in his words) is "a lazy bum." But rather than acknowledging these realities and dealing with them, Willy lives in a dream world where he *is* great, his children *are* successful, and people respect him.

Linda occasionally tries to pull him out of the dream world, and this is usually when she experiences Willy's most virulent outbursts. For example, Linda once tries to confront him about Biff's behavior

Linda: He's too rough with the girls, Willy. All the mothes are afraid of him!

...

Willy: There's nothing the matter with him! You want him to be a worm like Bernard? He's go spirit, personality...

Realistic Linda can never compare with the dream wife who agrees, smiles, nods...and never, ever, acknowledges the truth.