Can't, Not Won't?

"Did I interrupt something? I thought you were on the phone?" Tom asked when he noticed the way Harry abruptly stopped speaking and pocketed his phone.

"It's not important. Are you ready to leave?" Harry asked, choosing to take Tom's interruption as a sign that he shouldn't proceed with that yet. Perhaps he still needed to tread with caution.

It seemed like every time they were close to making a breakthrough in their communication someone always interrupted. First, it had been his father who barged into the guest bedroom just when Jade was telling him how she wanted to live rent-free in his head. Next, it had been the important call that entered her phone just when he was about to ask her what she had meant the last time, and now it was Tom interrupting just when he was about to ask her out. This had to be a sign. 

"Yes. Are you not?" Tom asked as he glanced at Harry's desk where his laptop was still lying open.