Question: are jace and clary back together?
Answer: Yes, yes, totally YES!!! In The Mortal Instruments, after fighting off idiotic psycopathic family members (like a psychic brother-Sebastian, and a psychic dad-Asmodeus) the Lightwood siblings, Jace and Clary return back to Alicante. Without Simon. But yes, Clary and Jace are together again.