>>19371205She's a pretty hardcore shut-in who can't maintain relationships. She's obviously busy with dance lessons and shit, so leaves messages hanging, but once a certain amount of time passes it feels too awkward and she retreats into her shell because she cannot deal with awkwardness. That's what I'm guessing. If a message is only a few days old, I'd imagine she goes "It's okay, I'll get back to them soon." But the longer time goes on the more awkward it probably feels for her and she tries to hope the issue resolves itself on its own. That's my guess.
Out of all Holos, she seems to have almost nothing resembling a proper social life.