Must a husband and wife make up for (the fast) and offer expiation if intercourse occurred during the daytime in Ramadan without ejaculation, and then the husband doubted whether a very small amount of fluid that he did not know was semen or prostatic fluid had exited?

Vaginal penetration invalidates the fast and necessitates expiation according to the consensus of jurists, regardless of whether ejaculation occurs or not. There is no validity to the claim that penetration without ejaculation does not invalidate the fast.

The emission of semen without intercourse invalidates the fast according to the majority of scholars, if it results from direct contact or foreplay. The fasting person must avoid anything that leads to this.

One who is ignorant of the prohibition of intercourse during the day in Ramadan is excused. However, one who knows the ruling but is ignorant of the penalty is not excused and is liable for expiation.