As Zooey Deschanel was the lead of the popular sitcom, many fans wonder why Jess left New Girl temporarily in season 5. Created by Elizabeth Meriwether, New Girl followed Jessica Day (Deschanel), a bubbly, young teacher who, after discovering her boyfriend cheated on her, moved into a loft with three complete strangers: Nick Miller, Schmidt, and Coach, who was quickly replaced by Winston, though he did return. Aside from that, the main cast remained the same – except in season 5, when Jess left for a string of episodes.
https://screenrant.com/new-girl-season-5-jess-jury-duty-deschanel-pregnant/