The root word of mortician is "mort" which means death in Latin. The term mortician is derived from the Latin word mort- (“death”) plus -ician. A mortician is an undertaker.
A root word has no prefix or suffix. it constitutes the most basic part of a word.
In linguistics, a root word holds the most basic meaning of any word. It's what's left after you remove all the affixes.
I would think that "insensitive" meant that his other girlfriends thought he didn't care, or he was a total idiot or soemthing. Just something like that. I hope this helped a little bit love!