Due to academic reason...
academic 已经包含"学业"的含义了
如果收信人是了解你生活的人 他自然会知道那是因为你大学的学业
若还想详细一点,可以像这样注明以下是因为大学的关系 我个人认为没必要 这很隐私
Due to my current university studies...
学业 academic career; courseofstudy; schoolwork; Education;
for the reason of my education/academic career/courseofstudy...
OK?
I have to give up this practice chance because of the courseofstudy
because of my studies....