Is the fast of one who dreamt of having intercourse with her husband and doubted the nature of the fluid that descended valid? And is the fast of one whose husband caressed her after Iftar, and fluid descended from her, then she slept and woke up after Fajr valid? If it is not valid, does she have to make up the fast and offer expiation? And is the fast of one who saw something that aroused lust at work, and semen descended from him, valid? And what is incumbent upon him if his fast is not valid?

Purity from janabah (major ritual impurity) is not a condition for the validity of fasting. If you felt something descend after foreplay with your husband, it is either maniy (seminal fluid), which necessitates ghusl (ritual bath) if accompanied by pleasure, or madhiy (pre-seminal fluid), which necessitates wudu' (ablution) and washing the affected area if not accompanied by pleasure. Your fast is valid, and you do not have to make it up.

As for the husband's fast, if he repeatedly looks and maniy descends from him, his fast may be invalidated according to some scholars. However, if madhiy descends, his fast is not broken. If he looks once and then averts his gaze, his fast is not invalidated whether something descends or not, because the first glance is excused. A believer must lower his gaze from what Allah has forbidden, both inside and outside of Ramadan.