People disappeared all the time.
It was a fact that Mami knew quite well. First it had been Madoka. She had came back, for that one brief day. But she had been taken away from them just as quickly. That first time felt like someone had ripped her still-beating heart straight out of her chest. The second time wasn't much better either. Then it had been Sayaka, in the midst of the confusion with SHODAN. By then the pain had dulled a little, so perhaps Mami was adapting to it. Then Homura was returned to the pods, only a short time after they had established... something. Mami still wasn't sure what it was, but it had been nice.
Then Madoka had returned, right around the time Homura was repodded. It helped dull that pain, and Mami was so happy. But at the same time, she was worried. She had suffered through her friends leaving several times over the months she'd been on the ship, and she didn't want to deal with that again. But she couldn't just stay away from Madoka. Her friend needed her, just like she needed Madoka. So going against her common sense, she proceeded to enjoy the weeks following Madoka's return.
So when she awoke and noticed the bed opposite hers was vacant, and after she spent the entire day reaching out and trying to grasp even a hint of that new yet familiar magical energy... something broke in her. But she didn't cry. She didn't scream. She didn't lash out in pain or frustration or anger, like she might have months ago. It's like she's been submerged under water. Everything is muted; her surroundings, her thoughts... even the pain in her chest - which she's sure should be reaching an unbearable level at this point - is just a dull ache.
She doesn't know how long she wandered the ship after that. She doesn't acknowledge any fellow crew members who might pass by - and should they, it doesn't take much to notice something's... off, about the girl. She moves mechanically, like a puppet slowly being dragged by its strings.
Eventually, Mami ends up in the Obs Deck, slouched over on one of the many chairs scattered throughout it. She's rolling her
Soul Gem absently between her fingers, watching the gathering dark blotches in the golden glow. The light from the gem doesn't seem to reflect in her eyes, either, which gives her a bit of an eerie look right now. Do you dare to approach?