What's Wrong with Going to a Magic Academy to Find a Wife?

I've been single for years and still don't have a wife. At long last, I took some medicine and got twenty years younger. I was planning to head to the academy and flirt with a female teacher, so I could finally settle down. But somehow, I didn't win over a teacher and ended up with a bunch of students instead. There's an elf princess, the Demon King's daughter, and even the Dragon Emperor's granddaughter getting involved. Get lost! I don't want to be an old man preying on young girls!