Because sometimes, your students become good friends.
When I taught at a community college, I had two classes of students that I taught the entire Calculus sequence and Differential Equations. That means I had them for four back-to-back-to-back-to-back courses. Being at a community college, the classes were small. The Cal1's had around 25, but after that, the numbers dropped to around 12 and steadily fell from there. In that kind of setting and having them for so many classes, you can't help but get to know them. This is how I met Zach.
At the time, I was 26, about the age of an older sister to the traditional student, and though I make it clear that I am in charge and require a lot of hard work, I don't run my class like a warden. I'm approachable, whereas most math teachers are feared, which is why Zach never hesitated to ask questions or seek help. When his house caught on fire one Sunday while his family was at church, he came to my office to talk to me about it.
After he finished Cal1, I recommended the college hire him as a math tutor. He needed a job, and although it didn't pay as well as some other jobs, it gave him time to do his homework. He had Physics with L, who was a year behind him in school but only two years younger than me. When the tutor lab was slow, L would often go over and help the Cal and Physics students with both classes. That is how Zach and L got to be friends, and when they both transferred to the University, L continued to tutor Zach in his Physics classes.
He would come over to our apartment, and while they sat at the table doing Physics, I made dinner. We'd sit around and watch TV or just talk. L taught Zach how to play chess, and eventually, we started a D&D game. After the Physics classes, he stayed in touch. We'd go out to dinner once a semester and email.
Zach graduated four years ago, got a job, and moved back home. Even though he wasn't nearby, he started playing an online game that L and I play, so we played together. Then, Zach quit his job (which he hated) to go back to school to get his masters. He had to stop playing games, and so we sort of lost touch. We would email once or twice a year. Hey! How are you? Good, and you? kind of things.
And then just last night, he called. He has one project left to get his masters, has a job lined up for when he finishes, and wanted to know if we were still playing Diablo II. "We actually just got back into it," L said. So, we all got online and start playing and chatting. I wrote, "It's so good to hear from you. Sorry it's been so long. I suck at keeping in touch," to which he replied, "Me too, but even so, I still consider ya'll some of my best friends."
Of course, not every student becomes a friend, but when they do, their success is doubly rewarding.