The way Carl and Sophia reacted to each other is the reason why I am very sad of her demise. Their friendship is cute in the comics, but we never have a chance to see more of it in the TV series. Sophia and Carl would have been a cute couple, but that was taken away by the cold hearted Kirkman.
Season 2 kinda sucks anyway. The creators of the TWD really screwed on a subplot about finding Sophia.
Was? They still are friends, I think. She now lives in Hilltop and Carl is with Negan, but everything was well at the moment they say goodbye, so maybe (If he isn't dead/too damaged) they can still be friends.