He poignantly recalled the happy days that would never return.

poignantly 是形容词 poignant 的副词形式。poignant 来自法语，原意是"尖锐的、刺痛的"，引申为"令人痛苦的、心酸的"。poignantly 表示"痛苦地、心酸地"，强调回忆带来的强烈情感冲击。