well im ruling out a molt seeing im sure you know about some being crabby during that time also and if she is going through maybe both at the same time ...could be the extra with the temper tantrums...i still recommend more darkness than what she is getting also...to 16hrs..with no ill affect to her...
is that cuttlebone flavored by any chance and do you also use a mineral block? If you do is she touching that? Mineral blocks are better too than a cuttlebone...but from what your saying she is destroying and not eating the hard part ..thats some bite on that little girl to be doing that...geeeeeeeesh.
I also still say separate them because something is frustrating her to all get out and where you say she would rather be alone maybe she is telling you something here..is her beak ok? Not extra long or anything?
im not sure whats normal for HER giggle at this time...myself ive never heard of a bird doing that not to say some dont...just ive never heard of it. Most wont even touch their cuttlebones. But here is a thought...if she is hormonal ...she wants to shred something for sure and if she doesnt have anything else to shred seems like she found something to appease that desire.
id say remove the cuttlebone and get or leave a mineral block in there...and try some powder or liquid calicum for awhile just till she forgets about this ...and no brocolli or parsley or spinach those are calcium inhibitors.
sorry i cant think of what this may be all about other than what ive mentioned.
Its got me stumped..other than to make those suggestions.