heartless

Without feeling, emotion, or concern for others; uncaring; cruel.

His heartless actions and cold manner left her saddened and feeling alone.

The world is a dangerous, violent place […] and the only true refuge from this heartless world is the family.

Without a physical heart.

Listless, unenthusiastic.

Near-synonyms: spiritless, unhearty

Without courage; fearful, cowardly.

Cecilia then, though almost heartless, resolved upon talking with Mr. Harrel himself […].