بسم الله الرحمن الرحيم
The husband and wife should avoid this act in the state of fast. However, if the husband did not penetrate in the vagina of wife, rather the husband discharged due to rubbing the outer part of vagina only then the fast of the husband broke out. The husband should make only the qadha of the fast not kaffarah.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.