I've had to do it due to hospitalizations. My parents were understanding about the withdrawals. I also did something a little different once. I took an "Incomplete" in a class and was able to finish my work at a later date, after the course had ended. If you feel you might be able to finish the work at a later date, you could always go for an Incomplete, but if not that's okay too. Please don't feel bad about having to withdrawal from a class.