The adjective ardent means exhibiting strong feelings.
Synonyms are avid, keen, passionate, or zealous.
The word origins from Old French (14th century) ardant meaning “burning, hot, zealous” and from Latin ardentem (nominative ardens) meaning “glowing, fiery, hot, ablaze”. It is also used figuratively meaning “of passions”, from present participle of ardere meaning “to burn”.
She was no longer an ardent girlfriend.
Jake had always been an ardent grandson.
His love was ardent and she reciprocated it with equal feeling.