Here's what many psychologists feel about grief. My experience is that these stages aren't really steps on a ladder so much as points in a circle that are visited. They're not always experienced in this order, and sometimes a station is re-visited.
My experience in grieving the end of my marriage was a longer process. Some of these stages- I didn't even realize that's where I was until I looked back. Hindsight is 20/20!
1) Denial- I was deeply in denial even during the whopping 6 weeks of our courtship. My excuse: love makes you stupid. He pushed for things to progress much faster than I was comfortable with. Friends warned me that this pushing was a display of flagrant disrespect for me and my natural (and completely healthy) sensibilities. I should have listened to my inner voice that screamed, "TOO FAST!!! SLOW DOWN!!"
2) Anger- For me, this came after the bargaining, when I found that bargaining didn't get my needs met. I was frustrated and angry that I didn't matter to him, that my needs and my unhappiness didn't matter.
3) Bargaining- I started this somewhere in our first year of marriage. I remember asking a month and a half before our first anniversary (the week of his birthday), how I needed to present my needs, how did I need to word things so that my needs were important enough to him. He said he didn't know. In other words, he acknowledged that I wasn't important to him. And that it was my job to beg for his attention. And that he wasn't going to do a darn thing about my unhappiness or his neglect.
4) Depression- I don't remember specifically feeling down and hopeless. I tend to be a person of action, so resignation, sitting and doing nothing is not really in my nature. At one point, I went on vacation, was away from home for a couple weeks.. and I didn't particularly want to go home. I certainly didn't miss him.
5) Acceptance came two and a half years in, when I realized that he wasn't going to change. When I realized that I didn't matter to him, and that he wasn't going to change, my first thought was that I couldn't stay.. and therefore I had to leave.