그이야기는하지않고싶어요 expresses that you prefer not to discuss that topic. 지금은말하기어려워요 emphasizes the present. “Now” does not promise a future answer.
Situation or form
Korean expression
화제를거절
그이야기는하지않고싶어요.
세부정보만거절
자세한내용은말하기어려워요.
일반적인범위만답하기
서울에살아요. 자세한주소는말하지않고싶어요.
다른화제로전환
대신주말계획을이야기할까요?
하고싶지않아요 can also express not wanting to do something. Our target is 하지않고싶어요, while natural alternatives are allowed. A brief boundary need not be followed by a long explanation.