unfaithful vs unfaithfulness

unfaithful is not a noun while unfaithfulness is a noun.

Word	Noun	Adjective	Verb	Adverb
unfaithful	No	Yes	No	No
unfaithfulness	Yes	No	No	No

unfaithful (noun)	unfaithfulness (noun)
	the quality of being unfaithful

unfaithful (adjective)	unfaithfulness (adjective)
not true to duty or obligation or promises
having sexual relations with someone other than your husband or wife, or your boyfriend or girlfriend
having the character of, or characteristic of, a traitor
not trustworthy