What do you mean by can't stay at the end? Listen im sure its not a big deal either way. But you have to remember that these interviews are setting you up for the rest of your life. I know we have a lot going on in our lives, but these are incredibly important moments. You can choose not to go, which I am sure will be totally fine. But if I were an applicant like you (I was a year ago) I would use every damn opportunity to make a good impression -- especially at a school where the interview pool is 300 and very small. Again, that's just me.