When Robert watches Giselle sleep on the couch, and decides to let her stay for the night instead of kicking her out, like he planned.
Robert is cynical and utterly unromantic, but he is obviously falling for Disney Princess-turned-real Giselle. When they dance at the ball, romantic song in the background, Robert starts softly singing along for her... even though he earlier said in the movie that he "doesn't dance" and "doesn't sing." Cue any girls watching to movie to go "Awwww!!!"
The True Love's Kiss scene. Seeing that Edward's kiss has failed to wake Giselle, Robert goes over to her and kisses her. Giselle's eyes flutter open. She looks up toward Robert, and whispers, relievedly:
Giselle: I knew it was you.
When, at the end, Edward ends up with Robert's girlfriend, that's a very short but very heartwarming scene. For that matter, when you think about Edward's character, you know that he did really love Giselle... but when he realized that his kiss wouldn't work, he turned around and asked Robert to do it. It showed that he was very open-minded, good at accepting the truth and the inevitable, and would then proceed to look for other available solutions.
Edward's delighted expression when he realized that Giselle and Robert were obviously meant for each other.
"It's a perfect fit." Her expression totally perfected the scene.
Throwing away her cell phone at her wedding to Prince Edward: goodbye real world hassle, hello wedded fairy tale bliss!
Just consider the set-up of the scene. Nancy's clearly upset about how her long-time fiance has gone off with another woman, but is really trying to hold it together and be mature about the whole thing. And Edward, whose own fiance has just left him, sees her and goes to talk to her, even though he hardly knows her at all. And think about how it is in his fairy tale view of the world. Him trying the slipper on her is him really thinking she's the one for him!
In a grander sense, just look at how positively Giselle affects the world around her just by being herself. In contrast, our cynical, imperfect "real" world tried very hard and failed to break her sunny spirit.