The first girl I liked I began liking when I was 10, and I liked her for over two years, from February 2010 to March 2012. That, over time, proved to be a disaster.
That time I liked her was from towards the end of my 4th grade year to the end of my 6th grade year (the 2009-2010 school year was my 4th grade year, and the 2011-2012 school year was my 6th grade year). However, I knew from the day I began liking her in February of 2010 that it was a long shot. I had only known her for six months (we never met until we were in the same gifted class with the start of the school year in August 2009), and I had hardly talked to her at all during that six month period in 2009 and 2010. And, by the spring of 2010, problems became visible.
First, in April that year, just a month before my 4th grade year ended, I had said something that I shouldn't have said to this guy in my class (it's a long story, so I won't bother going into the details), and that significantly damaged my reputation in the class, and she started being mean to me. Also, around that time, one of her friends came up to me and started talking about how I liked her (even though I had never told anybody since when I began liking her two months earlier), and even though she wasn't around to hear it, it was really weird and awkward as I figured that since I had never told anyone (and never did until after I stopped liking her in 2012), no one would be able to know.
The fact that this had all been happening just two months after I began liking her were signs that a disaster was coming. Although no one confronted me about it for over two and a half years after April 2010, the idea of being in a relationship with her was just becoming more and more out of reach, and that's part of the reason I gave up on her in March 2012. She and I were of different "stereotypes" after all, and eventually, although no one asked me about it between April of 2010 and December of 2012, after I gave up on her, it seems like a lot of people found out. During my 7th and 8th grade years (the 2012-2013 and 2013-2014 school years, respectively), we had Christmas dances at my middle school, and after the one in 2012, this guy came up to me asking if I took her to the dance, and I had to explain to him that I had given up on her nine months earlier, and it was so awkward, bizarre, and annoying...
That wasn't the only crush that ended in a disaster, either.