What is the ruling regarding someone who breaks their fast on a day in Ramadan without sexual intercourse, and is expiation (kaffarah) required of them? And what is the most authoritative opinion on this matter?

The preponderant view is that whoever intentionally breaks their fast in Ramadan, without sexual intercourse, must make up that day and repent to Allah Almighty for violating the sanctity of the month. This is the opinion of the majority of scholars. As for expiation (kaffarah), the majority view is that nothing is required of him by way of expiation, while others hold that the major expiation is obligatory.