Ginta saving both Alan and Edward when it seemed that wouldn't be possible.
In the anime, Chaton doesn't attend the party that was designated for MAR Heaven and stays outside feeding a baby Loco. Alan looks for her outside and asks her why she isn't in the castle with them. She turns away and starts crying and tells him that she's a Chess Piece and would only cause problems for him if she stayed any longer. In her mind, Loco insists that Chaton is playing tricks again and asks the audience Who Would Be Stupid Enough to listen to her? Cue, Alan goes up to her, takes her hand and gives her a communication ÄRM telling her that this would allow them to stay in contact. He then tells her that she's a member of Team MAR now and if anyone tried to say something about it otherwise, he would always protect her. Cue, she smiles at the ÄRM and then hugs him. She then asks them when they're going to get married. Alan freaks out and shouts what she was talking about and how he never mentioned anything about marriage. However, the way he gives her the ÄRM is similar to how a man asks a woman to marry him.
In the anime after Snow snaps at the King for killing Nanashi and pretty much ends up being burned to death. Her spirit meets her Earth counterpart, Koyuki. The two merge so they can be with Ginta when he makes it back home.
The reason this is so heartwarming is because of how big of a Woobie Snow really is. Never meant to exist, simply a copy of someone else, desperately wants to be with Ginta. It's just heartwarming how such a tragic character ended getting her happy ending in the end.