I'm not sure about that. Even after reading it despite the context it's still rather debatable to me. Like it's been said, the preview opens a huge can of WTF and even when the finale is shown, it might just completely depend on how you interpret it.
I'm sorry but I cannot agree with you. I'm afraid that you missed the entire subtle story-telling from Cross Game in true Adachi-style in the entire manga. The ending is so obvious, unless you favored another pairing.
(I posted my reply to your post on your wall instead of the CG-thread to avoid spoiling others and causing unnecessary drama in the last week of Cross game)