Do Elizabeth Midford and Ciel Phantomhive stay together even after Ciel turns into a demon in Season 2 episode 12?
At the end of that episode, it was shown that Ciel went to leave his mansion along with Sebastian. Sebastian then jumped off a cliff with Ciel on his arms. Considering this, it is very likely that Ciel didn't stay together with Elizabeth. He left her (dumped her, whatever you call that) to go with Sebastian, possibly to the underworld, considering the settings of the manga and anime.