If you ever saw the movie "Bambi," you know exactly how Winnie feels the first time she lays eyes on and meets Tuck. She is instantly and hopelessly "twitterpated" as Owl would say. If you haven't seen "Bambi," then none of that makes sense. She's instantly and hopelessly in love with Tuck. She's in love with his hair, his smile, his face, his clothes, etc. He's just "glorious" to look at.
"And he seemed so glorious to Winnie that she lost her heart at once. "
Once again, literature comes to further perpetuate the hopelessly romantic ideal of love at first sight. I haven't seen this movie, but I imagine the scene has Tuck's hair and clothes glowing with special lighting and slow motion. I'm sure that you have seen that kind of thing done in movies before. The thing about Winnie's meeting Tuck for the first time is that is exactly how the text describes the scene.
"The golden morning light seemed to glow all around him, while brighter patches fell, now on his lean, brown hands, now on his hair and face, as the leaves stirred over his head."
The only thing the description didn't do is make Tuck into a sparkly vampire (I'm talking to you Edward Cullen).
By the way, all of this is before Winnie even says a word to Tuck. She only falls more deeply in love with him after he introduces himself to her.
"I'm Jesse Tuck," he answered. "How do." And he put out a hand.
Winnie took his hand, staring at him. He was even more beautiful up close."
Basically, meeting Tuck makes Winnie feel all warm and mushy on the inside with butterflies flitting around in her stomach too.