Grief is the natural response to loss — most often the death of someone we love, but also any significant loss: a relationship, a home, a job, a pregnancy, health, or a future we expected. It isn't only an emotion. Grief shows up in the body (fatigue, appetite and sleep changes, a literal ache), in thinking(difficulty concentrating, disbelief), in behavior(withdrawing, searching, avoiding reminders), and in spirit (questions of meaning and faith).
It's worth separating two words. Grief is the internal experience of loss. Mourning is how we express it outwardly — through ritual, culture, conversation, and time. And bereavement is the state of having lost someone. All three are deeply shaped by culture, and there is enormous, healthy variation in how people move through them.
There is no 'right' way to grieve
Some people cry constantly; others rarely. Some need to talk; others need to do. Grief can come in waves long after others expect it to be "done." None of this is a sign that something is wrong — grief is as individual as the relationship it comes from.