In this intriguing letter from 2015 to his lady friend, it appears that she's slowed down her correspondence frequency with Hernandez and he's starting to get concerned.  They apparently haven't been getting along recently and Hernandez was getting upset because she is "a very good person/friend."  He apologizes for writing something nasty previously and explained that her last "negative letter hurt me" and "I am a really good person with a great heart."  Interesting that he sees himself that way.  The letter comes with the original envelope from Hernandez which is stamped from the Massachusetts Corrections Institution.