Relationships.

I think it's fine to maintain a relationship while you're in school, but that can prove to be difficult for some people. I've known a lot of people who didn't have a serious relationship while they were in school because it can be a distraction. I also know people who did have a serious relationship while in school and managed to balance both time with their boyfriend/girlfriend and time for studying/maintaining good grades. I ALSO know people who had a serious relationship and didn't balance school and love. I have a few friends that spent all their time maintaining their relationship and completely neglected school, and by doing so, failed all their classes. It just depends on what you're able to handle. If you're hoping to maintain a serious relationship then that's going to take a lot of work.