They must not have been very good "friends" if so many years went by after graduation and they didn't contact each other once. I can understand why Haruto didn't contact Chikage since he didn't think she liked him (and he was right) and Chikage didn't contact him because she didn't really consider him a friend, just her rival and the contest ended when they graduated. No doubt we will probably have to watch Haruto suffer even more as a parade of men continue to vie for Chikage's affection all the while she still only considers him a rival.