If you believe she was depressed; I understand and relate to it. Death can be a release. Pre-suicide, it feels as though you are about to just explode. If you're in the middle of suicide, or have suicide planned out, you feel release knowing that this pressure will finally end, as most people who want to seriously commit suicide have been depressed for a extremely long period of time. Knowing there is finally a end is extremely releaving.
If you believe she was still asleep when she jumped; I also know the feeling of being locked in a dream and simply wanting to wake up. Sometimes a feeling you're used to (Say, a pinch, maybe?) just won't have the shock in it anymore to take you up in 'tighter' dreams.
Either way, I feel that her jumping off was validated and I feel as though I fully understand how she felt.
Sorrow and regret. I played it so often, I grew attached to it and her by an extension. I jumped into the whole game blind. the only thing I knew about was Uboa. So my heart was shattered when she jumped. I pressed every single key on my keyboard, hoping she'd come out of nowhere, alive and well. after pushing every key but enter, I realized that it was futile, and cried. I grew so attached, I never wanted the dream to end.
I was shocked at first, then I tried to "wake up" with by pressing all the keys I could.
After a few seconds I felt guilty. Like there was something I could have done to save Madotsuki but I didn't do it.
Then I got a bunch of weird feelings when I realized how attached I had become to a videogame character who never speaks and is never given any background or anything. Just a sprite with your projected thoughts when you try to analyze her dreams…
I was really depressed and I felt guilty at first. I watched the final screen for a long time and thought about what Madotsuki might have been through in her waking life.