Throwing this out there, so speculation galore based on experience.
My guess is that Kaylee planned on staying the whole year, maybe even if she already had enough credits to graduate. Then the internship came up and it worked out so she was offered a job. From people I know, any of the following might have happened:
She ended up with enough credits to graduate, and decided on early graduation.
She didn't have enough credits to graduate, but requested that her internship/job count as enough credits to graduate (I know three people who did this)
She did not have enough credits to graduate, but requested to graduate with special circumstances (she had a job lined up) ( I know one person who got their degree this way)
In any of the above scenarios, she would not have known she wasn't staying the entire year until the situation arose where she was going to graduate early. So yes, she only stayed a few months, but that likely was not the original plan.
So to me, not odd at all that she only stayed a few months. Having been offered a job, and one far away, there was a lot to make choices on. (Boyfriend, time off before heading off to a job, graduation, money still owed on the lease, what to keep and what to let go, dog-who would get custody of Murphy?, etc)
JMO and thoughts.