Hermione would never tell anyone this, but she was jealous of Harry and the Weasleys. Why? Simply put, because Mrs. Weasley made them sweaters.
When the boys wore theirs during the cold months when they were searching for horcruxes, she nearly started sobbing every time she saw one. Mrs. Weasley loved them enough to take the time to knit a sweater with their first initial on it, and her parents were off in Australia, having forgotten she existed.

Logically, she understood that the Weasleys were the closest thing to a family Harry had ever known, while she had 2 loving parents, but she never got anything so heartfelt as a handmade gift. If she wanted something for Christmas, she'd tell her parents what it was, and they'd get it for her. They loved her, of course, but their understanding of her need to keep the Wizarding world a secret had caused a rift between them, they were distant, and at times appeared uncaring. For quite a few years, now, she had asked her parents for a knit jumper with a large 'H' on it, but they were never able to find one.
Sometimes it was hard to force out a 'Happy Christmas' when Harry, Ron, Ginny, Fred, George, even Percy were sitting around the Gryffindor common room in their sweaters.

She was old enough and mature enough now to honestly wish everyone a happy Christmas. She now shed tears, not for herself, but for Molly, who still made matching 'F' and 'G' sweaters for George, the one lumpy package left under the tree that George and Angelina took home unopened.

Ron had convinced her to send out their engagement announcements as Howlers, and in a few days the owls came pouring in. Harry, Ginny, Fred, and all their friends found it amusing. Unfortunately, Andromeda was miffed that it had woken Teddy from his nap, but she congratulated them all the same. Molly and Arthur were so excited they apparated over, Molly giving Hermione a big hug. Ron's ears turned red in embarrassment as Arthur clapped him on the back.

That Christmas, Hermione's smile made her cheeks ache as Mrs. Weasley passed her a familiar lumpy package. Her fingers shook as she pulled the purple sweater over her small baby bump. Her tears spilled over when she looked up to all the Weasleys smiling back at her. Ron laughed and hugged her, followed by Harry, Ginny, Molly, George, and Arthur.
"Happy Christmas, 'Mione." Ron whispered in her ear. "You're part of the family, now, and we wanted you to feel like you belonged." She saw a twinkle dancing in his bright blue eyes, and knew that he had seen past how the only sweater she ever borrowed from him was maroon with a large 'R' on the front.
"Happy Christmas, Ron."