In Harry Potter and the Deathly Hallows: Part 2, we see Harry and Ginny kissing, proving they were in love and later they married. But in Harry Potter and the Half Blood Prince, we see Harry trying to impress another girl in the hotel in the start of the movie. So were they not engaged in Half Blood Prince? There's also the whole angle of Ron getting jealous of Harry and Hermione during their trip in Deathly Hallows: Part 1 (even though he wasn't of a clear mind at that point). Was there any point in the movies where it was clarified that Harry and Ginny were an item before Deathly Hallows: Part 2 or was this just treated rather implicitly without even them realizing it themselves?
Harry Potter's earlier love interest was Cho Chang. She was dating Cedric Diggory in Goblet of Fire and later dated Harry during Order of Phoenix. They also share a kiss before the Christmas break, in the room of requirement.
However, she is torn between the memory of Cedric and her emotions towards Harry and thus their relationship never stabilizes. Later in Half Blood Prince, Harry starts to see Ginny, for who he always had a soft corner in his heart. They share a kiss right after Gryffindor wins the Quidditch Cup.
There's one scene in Half Blood Prince where Ginny and Harry kiss in The Room of Requirements. They are there to hide Harry's book after he uses Sectumsempra on Malfoy and almost kills him. The movie doesn't expand on their relationship after that, but the kiss happened in a different way in the books and they dated after that and only breaking up when Harry decided to strike out on his own after Dumbledore's death.