Unhappily

You doubtless mean well; but your ideas are unhappily mistaken.

Due to differing opinions between the two, they argued angrily, before leaving unhappily.

The line to Dunières consists of a series of breakneck descents almost invariably ended by a violent curve and followed immediately by a panting climb, on which the engine barked thunderously but failed unhappily to maintain its booked speed of 13 m.p.h.

Theodore Roosevelt […] added, perhaps unhappily, that he believed the US administration in the Philippines could learn a lot from the Austrian example.