The tone of a text message. This tone is FREQUENTLY misunderstood due to the lack of words and emotions, as is the nature of text messaging. Tone of Text can cause serious problems in a relationship.
Using the term "whatever" may be meant as "I don't care", "you decide", "I'm open". The receiver of that text message "whatever" can't hear your tone of voice and might assume you are being sarcastic or flippant or just plain rude, causing a Tone of Text misunderstanding.