As a response to 10 was holding it in so he could see all his companions again as himself and could do no longer when he reached the TARDIS. The build up of energy made it explode out of him whereas with 9 he just let it happen.
I actually cried reading this if I were the girl in the story I would die if that happened this show was my escape from my life and it brought me so many tears of happiness and joy. This just shows how much fandoms mean to people
"I think you need a Doctor. Like I said in an earlier pin/gif, if you'll notice, basically the whole scene is him watching her, because he's more concerned for what happens to her than the rest of the universe around them. LOVE THIS SCENE!