In the context of disorders involving emotion and mood, it can be inferred that Jenna is most likely suffering from Depression
Explanation:
Depression is an incredibly common but a very terrible condition to suffer from and has been seen to occur to people who have in the recent time lost someone that is close to them.
The usual symptoms seem to be there however one can never be sure without a proper clinical facility test and assessment.
The loss of emotions and moods, being preoccupied with thoughts of death and having the pleasure sucked out of one's life are often the telltale signs of onset of depression.