Is expiation obligatory for someone who had intercourse during the day in Ramadan, being ignorant of its prohibition, and had intended to break their fast before intercourse?

Whoever breaks their fast in Ramadan due to sexual intercourse is subject to the major expiation (kaffarah kubra) according to the majority of scholars, unless the two individuals involved were unaware of the prohibition of sexual intercourse during Ramadan, in which case there is no expiation for them due to the excuse of ignorance. However, if they are not excused by ignorance, then the expiation is binding only upon the husband, not the wife.