Well...This Is New - 30

I felt Jason's eyes on me during singing class today.
Those green irises gazed up at me from where they had been previously scanning something on his phone. I felt them as I walked by him to talk to Carrie, and as I walked back to my seat.
After singing class ended I realized I hadn't talked to him at all. As I walked with Jenny to history, I could see him walking in front of me, graceful and poised, and I couldn't help myself.
"Jason," I whisper-yelled, and he turned, and immediately smiled.
"'Sup?" I asked. "Hey...you have art class now. With Paul."
He watched me, and smiled confusedly.
"I have art class with Joe?"
"No!" He'd stopped, and I walked closer to him. "Paul!"
"Who's Paul?" He asked, grinning.
"You...the guy you sit with," I said. As soon as I was next to him, he started walking close to me, smiling and staring into my eyes.
"I don't know who you're talking about," he said.
-BACKGROUND INFO-
I told you about how earlier, Jason would frequently butt into my conversations.
One time, as I complained about Paul (this was the second time I'd interacted with Jason, ever) he jumped right into my conversation and stared at me.
"Whoa whoa whoa," he'd held up a hand, green eyes glinting. "I don't know this Paul guy...but he sounds like a little boy. You don't need an immature little boy. You need a man who's going to do it, and do it well, when it's time to do it."
I'd furrowed my eyebrows at this random boy who thought he knew my business.
"Do what?" I demanded.
Jason leaned close.
"Everything."
I stared at him, and then looked at Carrie, whose mouth was wide open.
Both of us burst into laughter.
And not long after that, Jason asked me how Paul was doing.
He asked me a couple times. I'd tell him the same thing. That things with Paul sucked.
And he'd see me with him. He'd see us walking together and laughing. Paul is not invisible. No, he is not.
-BACK TO TODAY-
"Paul!" I cried, looking at him. "My goodness...you don't know?"
"No," he said, chuckling. "I can't say I do."
"He's going to be so hurt," I said, grinning up at him.
He laughed. "You can tell him I'm sorry."
"He's going to be crying all over the floor," I shook my head, and he laughed harder, even though it wasn't that funny.
"I'm sorry, Emily, I have no idea who you're talking about."
"I'll see you later, Jason," I chuckled, forced to part due to different classes.
He chuckled, too. "Bye, Emily."
Now....
I'm wondering.
Why is he lying?