Is it permissible for a husband to leave his wife during intercourse after foreplay to do something unimportant, then return to complete the intercourse, knowing that this interrupts her pleasure? And is it permissible for him to ejaculate without satisfying her if she becomes angry?

The husband must satisfy his wife's needs to the best of his ability and her desire. It is disliked for him to withdraw before his wife has satisfied her desire, for the Prophet, peace and blessings be upon him, said: “When one of you has intercourse with his wife, he should be truthful with her. Then, when he has fulfilled his need, he should not rush her until she has fulfilled her need.” Some scholars view this as forbidden due to it depriving her of complete enjoyment. If the the wife becomes angry as a result, the husband must seek her forgiveness and appease her.