Our ethics should boil down to 'hug Mami more' and 'Help everyone'.
Things aren't quite that simple. Hugs, good intentions, and trying to help everyone alone aren't quite enough.
I do wonder what would happen to the others though, if they ended up in Deldore's barrier, I do know that us witching out is a bad end, but it would be interesting to ponder the effects of our minds would have upon the witch.
I'd rather not know to be perfectly honest.
Although... I think I do recall Firnagzen saying that we would end up seeing our Witch one way or another. Whatever that means.
On another note, how much does Homura know about what happened between Mami and Kyoko, and the exact specifics and reasons behind Mami's issues? Maybe we should ask?