While they were close friends during the "Harry Potter" filming, their relationship was always platonic. They have both spoken about their friendship and their mutual respect for each other, but never about any romantic involvement.
It's important to remember that actors often portray intimate scenes on screen, even if they are not romantically involved in real life. So, the kisses you saw in the "Harry Potter" films were for the sake of the movie and did not necessarily reflect their real-life relationship.