Why did Alison hate Spencer in Pretty Little Liars?

Answer 1

On the night that the girls blew up Toby's garage, Allison told Toby that she had watched through his windows and saw him and his step-sister, Jenna Cavanaugh, having sex. She told him that if he told on them, that she would tell everyone about him and Jenna.

Answer 2

Alison was mad at the Pretty Little Liars because they thought it was her and they were hanging out with Kourntey

Answer 3

because courtney stole her life.and pretty little liars also ruined it with there loser status.so all five of them technically stole her life.

Answer 4

Spencer was the only one who dared to stand up against Allison.