(2) And if the drops of semen fall on the body of my wife, does she need to do ghusl?
بسم الله الرحمن الرحيم
(1) It is lawful.
ويعزل عن أمته بلا إذنها وعن زوجته بإذنها الخ البحر الرائق 8/358’ قبيل ” فصل فى الاستبراء”’ ط: زكريا)
(2) If you ejaculated at the time of foreplay and the drops of the semen fell on the body of your wife then it is enough for her to wash that part, it is not necessary to have ghusl provided the wife is not discharged. But if you penetrated and the drop of semen fell on the body of wife while discharging the semen outside the vagina, then ghusl is wajib on both, as only by penetrating in the vagina ghusl becomes wajib whether ejaculation takes place or not.
Allah knows Best!
Darul Uloom Deoband