Grief can take many forms, I think. It doesn't necessarily have to be for a physical death. It can also be for the death of an image. Often people create personas of who we are, inside their own minds. Whether this has any bearing on reality is secondary to how they see us. My mother did it. She built up an entire other person of who she thought I was. Her hopes, ambitions, dreams for me. She had my whole life planned out. Who I was going to be, what I was going to do. From the cradle to the grave, pretty much. In her mind, she knew me, saw me. That it wasn't the same me I saw... well... to her that didn't matter. And the same is true, I think for many people, and many parents. They think they know who you're going to be before you do.
"Timmy's gonna be a doctor, he's so smart. He's gonna be like that handsome doctor off the TV, you know the one! The one who has the nurses eating out of his hand. And we'll be so proud of him!"
The grief comes because of the emotional investment placed in that erroneous image. That self-created persona. The emotions associated with loss are just as real. In a sense it's the death of a perception. One which, in a person's mind, has been almost willed into reality. And is ultimately a selfish one. But that doesn't make the pain any less real, or heartfelt. I don't think it's non-acceptance of who you are, because I think until a certain point after you come out to people, they have to adjust to the fact, and get over the loss of who they think you are. The death of a phantasm which has ceased to be.
Perhaps there does need to be a period of adjustment, or grieving, before people who create reflections of you inside their own heads are able to look into the mirror of your own soul instead.
That's my take on it anyhow.