Stiles is talking about girls like he wants to convince himself what he really feels. And, hey, only the unhappy and frustrated ones drink that much alcohol.

Stiles: "What's going on? Did you find Derek yet?"
Sheriff: "I'm workin' on it. You go take your test."
Stiles: "All right, dad, listen to me."
Sheriff: "Go!"
Stiles: "This is really important. You have to be careful tonight, okay? Especially tonight."
Sheriff: "Stiles, I'm always careful."
Stiles: "Dad, you've never dealt with this kind of thing before, okay? At least not like this."

The way Stiles says "Did you find Derek yet?" like there is hope if they didn´t find Derek´s body yet that he is still alive. He fears that his dad is getting hurt. He tries to warn him about how dangerous the night of the full moon is and still he doesn´t tell his dad the truth about Derek or werewolves. Stiles thinks about Derek all the time simply because Derek has become a huge part of his life.

Stiles had panic attacks after his mother died.

Derek is alive. He saves Scott from doing something really bad.

Stiles wears black and a white striped shirt. Derek is still in black.