There's a little bit throughout the series. ginny always has boyfriends, Ron and Lavender in the sixth book, Hermione and Krum in the 4th, Harry and Cho in the 5th and Harry and Ginny in the 6th/7th. The biggest romance is probably between ron and hermione which spans pretty much the entire series, but it doesn't pick up until the end and it still is not some epic romance.
These are not romance novels. Although it does contain a little bit, the focus of the series is more about courage and overcoming adversity than romance. So I highly recommend these books, but dint expect a constant romance.
