Look up the "Seven stages of grief", and then read Noel's pinned post at the top of the forum.
If you read all the replies, you'll see a classic example of people going through those seven stages of grief.
Which include, anger, disbelief, and depression.....among other things.
People LOVE Sonar, and when you lose a "loved one", be it a human or an animal, a car or software, you will feel a sense of grief and loss. In most cases the grief isn't as bad as if you lost someone close to you, but the signs are all there to a various degrees.