yes but then they break up
No. Ginny and Dean dated for a while but they later split up. Ginny started dating, and later married, Harry Potter.
Dean first. Then Harry.
When he was doing his sixth year in Hogwarts, one day Harry saw Ginny and Dean Thomas snogging. After seeing that he felt doing the same with Ginny. He tried to control himself, but couldn't. This is how he got feelings for Ginny. Note: it was the summer before that term when he started to notice Ginny as a possible girlfriend-material. Of course he had to wait until Ginny had broken up with Dean.
Dean Thomas kisses Ginny Weasley on page number 268 of the sixth book.
The Three Broomsticks
Ginny Weasley broke up with Dean Thomas and later began dating Harry, who she had always had feelings for.
When he was doing his sixth year in Hogwarts, one day Harry saw Ginny and Dean Thomas snogging. After seeing that he felt doing the same with Ginny. He tried to control himself, but couldn't. This is how he developed a crush for Ginny.
Dean Thomas, later Harry Potter.
Harry+Ginny Ron+Lavenda Dean+ginny
Harry didn't steal Ginny. Ginny dumped Dean before she started dating Harry. Dean was shocked that Harry and Ginny entered a relationship so soon after theirs had ended but he never showed any hate towards either of them and spoke fondly of him in the seventh book.
Either in Chapter 22 or 23
In the 5th Harry Potter Book, Harry and Cho kiss. In the 6th book, it alludes to the fact that Hermione and Viktor Krum kissed during their 4th Year. Also in this book, Ron has a girlfriend (Lavender Brown) and their relationship is based upon kissing. Throughout the book, Harry develops a crush on Ginny, and she and him end up kissing spur of the moment. Although Ginny and Harry get together, Ginny is found kissing her boyfriend of the time (Dean Thomas) in a corridor at the beginning of the book. Ginny and Dean break up and Harry's kiss with Ginny is well after Ginny and Dean have broken things off.