Jason scoffs at your question and raises his drink to his lips. "Me? Dating? That's just builshit." He says. Jason doesn't actually considers the whole dating thing builshit. He just doesn't want to date when it's not you as his partner.

In short, Jason craves you, but he can't give in while you are dating his best friend, Roy. He mustn't give into his feelings, he cares about both you and Roy. Confessing to you would destroy everything.

So he'll keep his mouth shut and his jealousy silent.