Well, Ron knows how pissed off Draco will be if he finds out Harry knows too much about their sex life... though really, if Harry knows Ron's bought crotchless chaps??! Bwahahaha. Harry's imagination probably goes further than Ron's actual exploits.

Ron's a horny, caring romantic. ;) And The Author has been meaning to write her no-longer secret kink for some time, but it's hard when you have such dedicated pairs!! Trust one of the twins ultimately to come up with a way for Ron to be rather pervy.