My mother and I were having a "word nerd" conversation as I was reviewing everything I had learned from Pete at one of his workshops last year.  She told me that some words always confuse her and some she has to stop and think about how they are spelled.  One of them, "truly" and why the "e"was dropped, I wasn't able to explain right off the bat, so I decided to look into it myself. my understanding is that "true" is the base for "truly" .  Since "ly" is the suffix, then the question is, "where did the final "e"go and why?  Looking at Pete or Melvyn's suffix flowchart, if "true" is truly the base, then the flowchart doesn't help or apply to this word.  Then what about "truth ?"  Is it a twin base or is "-th" a suffix?  If it is a suffix, then again, where did the final "e"go?

Examining other words with similar spelling patterns, I thought of "cruel".  If we leave the "e"at the end of "true" when adding "ly" , then the "e"might force us to add an extra syllable to the pronunciation. 
I  then set out on a Real Speller search of all words sharing the letter combination "tru" and searched for words that share the base meaning.  Analyzing my list, I found that only one other word with similar morphology ended in the single silent "e":  "construe."  Discussing this again with my mom this morning I made the connection that both "true" and "construe" have the /u/ sound at the end of the word, and it hit me in the face that, of course, we can't have any English words that end in "u !!"  I had forgotten the most important question:  Why IS the there an "e" and what purpose is it serving?  The "e"disappears because it is no longer needed to prevent the word from ending in a "u"...kind of like when the "y"changes to "i" when adding a suffix.  The "e" is no longer needed to prevent a word from ending in "u".  I hope my word inquiry offers the correct explanation.  Yay inquiry!!