Originally Posted by
mahlerfan
It is if the two flights are not booked together and the BRU to NRT flight is non-refundable.
Based on the screenshot provided, it's perfectly clear that this is a single itinerary that involves a codeshare flight. Multiple people have accurately pointed out that if the initial flight is delayed, the airline is still responsible for getting the OP to the final destination.
Missing the connecting flight could be described as anywhere between an annoyance and a major inconvenience. Calling a missed connection a "disaster" seems wildly hyperbolic.