They are just too cute smiling at each other. You can tell this is the moment when they both started to notice one another and became even more attracted to each other, even though they were both too obviously scared to verbally admit it.
Christmas was one of the very few times of year that Kurt was almost always in a good mood. It was just something about how everything looked with the decorations and snow and that everyone seemed to be nice for a change that made Kurt happy. This year wasn’t any different but his brighter mood wasn’t as obvious. It wasn’t that he was upset or he wasn’t excited for Christmas, but he couldn’t help but think about Blaine and how the other was going to be alone on Christmas. Kurt didn’t want the other to be alone on the day, especially considering he didn’t have a great relationship with his parents and wouldn’t be able to celebrate it with someone else, but he wasn’t sure if Blaine would be allowed to stay over, or if Blaine would even want to.
On Christmas Eve, however, Kurt finally came to a decision, and drove down to Blaine’s house. It took a little longer because of the snow, but Kurt wasn’t going to let that stop him from visiting the other. Eventually he got to the other’s house, and parked as far as he could get up the drive way. It was pretty damned cold, and as much as Kurt loved the snow, he didn’t want to be out in it for much longer. Kurt knocked on the door rapidly, bouncing on his toes as he tried to warm up as he waited for Blaine. Hearing footsteps, Kurt breathed out a sigh of relief and stepped back slightly.
“You’re coming over to my house” Kurt said, the second Blaine opened the door. “It’s Christmas Eve.. and you’re going to be spending it and Christmas alone, and you shouldn’t be doing that. You deserve to have a real Christmas, so you’re staying at my house for the next few days. So hurry up and run upstairs and get a change of clothes, because I think I’m going to freeze my ass off.”