What is another word for lack of fidelity?
Pronunciation: [lˈak ɒv fɪdˈɛlɪti] (IPA) 
When it comes to describing a "lack of fidelity" in a relationship, there are several synonyms that can be used. An unfaithful partner can be described as disloyal, unreliable, untrustworthy, faithless, or deceitful. Other words that can convey a similar meaning include infidelity, cheating, adultery, betrayal, and treachery. A person who demonstrates a lack of fidelity may also be characterized as dishonest, insincere, or uncommitted. Ultimately, the terminology used to describe a lack of fidelity will depend on the context of the situation and the extent of the betrayal. Regardless of the words chosen, a lack of fidelity can have devastating consequences for relationships and should be addressed accordingly.
