You can't blame Haruka for anything. She doesn't even know she's a "weak-willed, mentally unstable clinger." To her, it's only been a week. That's what the doctors tell her anyway. She has no idea it's been three years.

If they had told her right away, and she didn't fall back into a coma, I believe she'd come to the exact same conclusion she did at the end of the series. She would let him go. That's the kind of character she is.

Granted, it seems to take her another 2-3 years to finally get over losing Takayuki to the flow of time, but she knows it was the right thing to do.
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I wonder what will happen to Mitsuki in the alternate ending...She's not quite as selfless as Haruka, right now I can't see a good ending for her at all.