Yonatan was a lifelong Hassidic Jew and until his marriage to Roz, a bachelor. Roz was a recent adherent to Hassidism, having been born Jewish but having lived a largely secular life until six months previously. They were matched by a matchmaker and met shortly before they were married. However, at the wedding celebration, Roz started bleeding and collapsed.
Yonatan was very worried about Roz despite only having met her a few weeks before. However, Gregory House thought that Roz's recent embrace of Hassidism was a symptom of her condition and ordered treatment based on that assumption. When Yonatan found out, he was furious and demanded that House be removed from the case. However, both Lisa Cuddy and House convinced him House was the right doctor for the situation.
However, as Roz grew worse, Yonatan started getting worried at Roz's insistence that she not be operated on until after the sabbath. Yonatan was aware that although surgery on the sabbath is frowned upon, the commandment to preserve life made it clear that it was allowed. He even had a rabbi speak to Roz about it. However, Roz was insistent. As a result, Yonatan agreed to a subterfuge to convince Roz the sun had set by blacking-out the hospital corridors.
Before the surgery, House realized Roz's problem was a hanging kidney and that she improved when she was lying down and the kidney returned to its normal position. Roz was given surgery to stop the bleeding and put the kidney back in place.