Being emotionally numb was the symptom that really raised a red flag and made me realize something was wrong. My DP came on suddenly after a major panic attack induced by weed and the first thing I started noticing as I was calming down from the panic was that I had lost all my feelings for my boyfriend. Over the following days I sank into a horrible depression- and I have never struggled with any kind of depression or real anxiety in the past- and I just felt hopeless and like I wanted to die every second of the day.
I thought I was only numb to positive emotions, but it's been almost a year since the onset of my DP and I don't experience any emotions except for anxiety, fear and a sense of dread/ impending doom at times- but this has gotten substantially better with time. Not only can I not feel happiness, peace, excitement or love, I also don't get angry and can't feel sadness or grief. I didn't even blink an eye on the two year anniversary of my mother's death in August.
I can't tell if it's more frustrating to not be able to enjoy life or look forward to anything or to be unable to grieve and connect to the sadness and work through it.
I also don't feel anything after I cry, and sometimes I'd say I feel worse after I've been crying because I get all worked up and there's never a resolution or feeling of relief like I used to get after I cried. I also don't feel the endorphins after I work out at the gym.
So, you're not alone. I'm pretty sure a bunch of people deal with the absence of their emotions- or the numbness of them. They're still in there somewhere but according to my therapist the subconscious got emotionally overwhelmed at some point (by whatever the root cause of your DP was) and decided to just shut down instead of trying to process whatever was too painful or overpowering to handle at the time.
People often describe being able to intellectually understand their emotions- they realize that they must be sad because they're crying, etc. but they're just completely unable to connect with those emotions or feel them on any other level.