Is there anyone else who's madly in love with someone who's not in love with them?

I'm talking about actually being in love with the person to the point where it ruins your day and night,24/7, every second without that person is torture. If u don't get a hi from them your day feels empty. That's what I'm going through right now and it's brutal, I'm trying to detach but it's not easy,it hurts me so bad seeing her leave work without even saying bye to me ect. I hate it ( and I thought I had a chance which fueled my love for her)