When I talk to clients about grief, they often think I'm referring to the physical death of a loved one. But, I remind them that grief is much larger than that - yes, it usually refers to the mourning process over the physical death of someone. But, grief is also the process by which we mourn the loss of anything - even friendship.
For those who feel they must end a friendship due to too much ongoing conflict, the figurative "death" of the relationship can be traumatizing. So, I often advise those in the grieving process to actually contemplate the five stages of grief (denial, anger, bargaining, depression, acceptance), much like they would if they were mourning the death of a loved one.
And, I remind them that the five stages aren't linear. At one moment, you'd swear you were over the denial stage, only to find yourself right back there again. I let them know it's normal to bounce around from one stage to the next, too.
For most people, the grieving process takes up to a year - for many people, it will actually be much longer.
But, here's the rub - it's easy to get "stuck" in one stage or another. If you've been embroiled in conflict, you may feel like you want to stay in the "anger" stage forever. But, we all know that's not a good thing (in fact, that's when some people find themselves seeking counseling).
Bottom line - the five stages of grief aren't reserved for physical death. They're useful to mourn the end of anything, especially friendships.