Ginny is introduced in the first book Harry Potter and the Philosopher's Stone, as the youngest sibling and only daughter of Arthur and Molly Weasley. She becomes Harry's main love interest and eventually marries him at the end of the series.
So why did Harry choose Ginny over Hermione? Because Harry and Hermione were never a thing. And because Harry developed feelings for Ginny. He didn't “choose Ginny over Hermione,” because he was never interested in Hermione.
Ginny Potter became pregnant with her and Harry Potter's first child, James Sirius, after the Second Wizarding War and sometime in or around 2004. Ginny gave birth to the couple's second son, Albus Severus, about two years after his brother in 2006.
After years of build-up, Harry finally starts to have feelings for Ginny in The Half Blood Prince - and one of the first moments he realizes it is when he smells Amortentia, and it smells like 'something flowery he had smelled at the Burrow'... Ginny's hair!
At the end of Harry Potter and the Half-Blood Prince, Harry realizes that anyone he becomes close to is likely to become Voldemort's target. To protect Ginny, he reluctantly ends their relationship.
She probably picked up on it some time near the end of summer, before their sixth year, but she wouldn't have known for sure until around Christmas, I'd say, when the Hogsmeade trip took place, and Harry asked Ginny to join them, which he'd never done before.
What is the age difference between Harry and Ginny?
She is one year younger than both Ron and Harry. The author has said that Ginny's birthday is 11 August 1981, which actually makes her almost exactly one year younger than Harry (whose birthday is 31 July 1980) and 17 months younger than Ron (whose birthday is 1 March 1980).
After his relationship with Cho "fell apart" and Harry spent a good deal of time with Ginny at The Burrow in the summer of 1996, Harry's feelings for Ginny began to deepen and change.
Several years later, however, Hermione was forced to alter her parents' memories and give them new identities as Wendell and Monica Wilkins, to protect them from the Death Eaters. After the Second Wizarding War ended, Hermione found her and her husband in Australia and returned their memories.
Hermione and Ron finally had their first kiss during the Battle of Hogwarts in Harry Potter and the Deathly Hallows. Unsurprisingly, they got married not long after and later had two children, Rose and Hugo.
Ron first began to show signs of romantic interest in Hermione in their second year; he was irritated by her crush on Professor Gilderoy Lockhart, became so angry when Draco Malfoy called her a "Mudblood" that he tried to hex him, and was even more upset than Harry when she was one of the Basilisk's victims.
Her middle name, Luna, is a tribute to Luna Lovegood, a good friend of her mother, during their time at Hogwarts. This naming choice reflects the deep respect and affection Harry and Ginny have for these two individuals.
Harry Potter had a few love interests during his time at Hogwarts. Though he eventually settled down with Ginny Weasley, he also had a thing for Cho Chang in his earlier school years. Then, of course, there's his secret love for Draco Malfoy…
In the book, Harry kissed Ginny after Gryffindor won their Quidditch game, whereas, in the 2009 movie, it was Ginny who boldly kissed him, just before the pair disappeared into the Room of Requirement.
The fact that it takes both humour and looks to win his interest also explains why it took so long for Harry to notice Ginny sexually. It is not until the fifth book that Ginny starts to become comfortable enough around him to be able to display her true personality - and Harry starts to notice her more.
Their relationship grew stronger after the death of Cedric Diggory, but Harry suspected Cho of betraying their secret student group. Cho's lingering feelings for Cedric and a lack of chemistry between her and Harry contributed to their breakup, leading to Harry ultimately ending up with Ginny Weasley.
It is very likely that they married soon after Ginny completed Hogwarts, due to their friends marrying at a young age. Placing the marriage in either late 1999 or early 2000. Ron and Hermione get married sometime after the Second Wizarding War, presumably before their first child is born in 2006.
In the books there are plenty of reasons why Harry would like Ginny. She is smart, strong, funny, sassy, a good quidditch player, pretty... Even Fred and George mention that she is quite popular with boys. Harry and her spend a lot of time together in OotP where he gets to know her and becomes her friend.
According to Hermione, when Harry bumped into Ginny while climbing through the Gryffindor common room entrance under his Invisibility Cloak and under the influence of Felix Felicis, Ginny believed that it was Dean who kept trying to help her through the portrait hole and the two argued over it.
In the film, she only hugs Harry, and just gives a hesitant handshake to Ron (Note: This was the result of Emma Watson being hesitant to hug both Daniel Radcliffe and Rupert Grint in public view, with her hugging Radcliffe during filming having to be frozen for a few seconds to get the desired effect due to Watson ...
Anyway, Ginny had two boyfriends before Harry- Michael Corner, whom she met at the Yule Ball in her third year, and Dean Thomas, whom she started dating at the end of her fourth. Three. Michael Corner, Dean Thomas and Harry Potter.
In some parts of the saga, Draco even seems obsessed with Hermione. Even though he considers Muggle-borns to be inferior, he hasn't ever picked on one other than Hermione.
