I'll be honest, I can't see Tsukiko x You working out in the long run. She's infatuated with You and that's good, but You is way too flighty (if not outright airheaded) to really match someone as serious as Tsukiko. I don't mind the serious/airhead combination most of the time, such as in Kazuma Kowo's "Lovesick Over My Best Friend", but I can't really get a good feel for it here.
It would have been nice if there was more time spent on showing the deeper relationship between Umi and Tsukiko than just that one page or so of conversation and a throwaway line about how they talked a lot before getting together though.