romance vs love affair

romance and love affair both are nouns.

Word	Noun	Adjective	Verb	Adverb
romance	Yes	No	Yes	No
love affair	Yes	No	No	No

As nouns, romance and love affair are synonyms defined as:

romance (noun)	love affair (noun)
an exciting and mysterious quality (as of a heroic time or adventure)	a relationship between two lovers
a novel dealing with idealized events remote from everyday life
a story dealing with love
a relationship between two lovers

romance (verb)	love affair (verb)
tell romantic or exaggerated lies
talk or behave amorously, without serious intentions
have a love affair with
make amorous advances towards