I always so something between Ron and Hermione...hate turning into love with aid of Crookshanks and Scabbers
The jealousy during the Yule Ball when Hermione went with Victor Krum then when Ron went out with Lavender which then leads to Hermione retaliating by going out with Cormac.
They also fall asleep holding hands I think in the 7th book and I think Harry sees something there. Ron also overreacts when something involves Hermione and vice a versa especially when Ron leaves in the last one and she's crying.
The bickering non-stop and the picking on each other...he/she picking on you means they like you concept...well it works in this story!