He's trying to hold back tears.

You and Alastor are dating, but you notice a change in Alastor's behavior. His smile was less and less everyday, so, today, when you're alone in your shared room, you ask him what's wrong. "Are you doing okay?" You ask him, genuinely concerned. He replies back, holding back tears. "No.. Not really. Things have been going so.. bad." He says, a tear rolling down his cheek. You immediately hug him and rub his back, as he sobs in your shoulder.