No further comment or speculation here about the reasons for her firing. I was interested so did some digging around, as I always hate to see anyone go down like this. (Heck, I am still recovering from the firing of Kago Ai cos it meant we never got W's third album!)...
This thread at JPLOP has extensive discussion, and especially on page 3 some possible reasons for her sudden departure start to emerge - in this case, it seems
lack of motivation apparently leading to simple failure to carry out her duties, rather than some boyfriend or other such scandal, are the believed reasons for her termination. Sad if this is the case, as it seems from the official wording that she was given a chance to fix the problem and have her expected graduation, but seems it may have just not meant that much to her. Then my mind starts to wander and I wonder if, as perhaps in the case of Fukuda Asuka,
maybe she was out of sync / being bullied by other members and lost heart and couldn't even care any more. I've seen is happen countless times in school settings in my professional roles... pure speculation of course, but sort of fits what we know or what others have gleaned.