My job colleagues think I'm weird. Should I quit my job?

The situation was fine at work for the past couple of years. I was in love with a female colleague for quite some time, but never said anything to her. I preferred to get closer and when the time is right to tell her how I felt. That time came and go a couple of times. I finally got the courage to tell her a few months ago (I know the exact date and time, but that would make me look weirder). She turned her back on me, like I never existed. I tried talking to her, to clear up things, but no luck. All I wanted was things to settle to a "just friends" status, because (I understand now) it takes two in a relationship, so evidently it couldn't be anything more between us. Maybe I looked distant or out of sync, I don't know. But people started to avoid me. It sounds silly, but if I see a colleague depressed I try to cheer him/her up. Communication became more and more difficult and as this situation persisted I starting talking less and less with them. Nobody cares if I'm there or not, except the company (not knowing how to deal with the situation, I started concentrating on work like crazy and impressed my boss on a few occasions, now I'm proposed for a promotion). So basically my career went up, my morale is very low and people think I'm weird. I'm thinking of quiting my job, because this doesn't feel right at all to me. Any suggestions?