Mental Mirroring

On February 2, 2018, a strange person found me. He told me that he kept living the same day over and over again, and I was the only person who changed every day. At first, I didn't believe it, so he walked me through his day, knowing everything that was going to happen, which made me have to start to waver and finally believe. The next day, I found that I was also trapped in this day, but I clearly knew before... Who is he? Who trapped us here?