This is not really a story of me simply being "clueless." More like "horrible at existing as a human being in every meaningful way."
Throughout high school there was a girl who was always very quick to take the same classes as me, get assigned to the same groups, etc. Outside of class she would often come to me to offer to study together, and I couldn't say no to her. But there was a "problem": she was an extremely kind, interesting, and attractive girl. So I thought Yeah right, like someone this wonderful could be interested in me! I actually had the biggest crush on her, but surely that was just a crazy fantasy on my part. I had low self-esteem, a bad situation at home, and was thoroughly screwed up when it came to interpersonal relationships.
So what strange confabulation did I construct in my teenage brain to explain why she was always trying to spend time with me? Surely she couldn't just want to be friends, and most certainly not anything more than that. Therefore she must simply be using me to do her work for her!!! Was I actually doing her homework for her? No. Writing essays for her? No. Helping her cheat on tests? No. In fact, she was very smart herself. But somehow I convinced myself that she was just interested in taking advantage of my intellect. Yes, I am the villain in my own story.
Not only did I fail to realize that she liked me [as would later be confirmed], but I was often testy with her, and sometimes made up excuses to avoid her.
And it gets worse.
I can remember numerous times when we talked, like really talked in a way I've never done with anyone else. She asked me questions about myself, the life I led, my hopes and dreams. On a few occasions I actually opened up and told her things I had never really told anyone else, like stuff about my physically abusive father. She responded with genuine compassion and I didn't even appreciate it at the time. As it turned out, her parents were neglectful and abusive as well, and she told me how her aunt and uncle took custody of her when she was in middle school, relating how much better things can get. I didn't completely blow her off or anything, but I was unable to appreciate just how open she was with me. And of course I rarely asked her about herself.
Now we get to the sexually clueless part. I can remember multiple occasions when she invited me to her house when "her aunt and uncle were out of town," and as usual it didn't even occur to me that she was interested in anything more than a study buddy, so I always made excuses and turned her down. She hugged me all the time, and I took it as a sign of pity rather than affection. She would blush at the drop of a pin when we were together, and I took it to mean she was laughing at me on the inside (yes I want to smack myself too). Now, to understand this in hindsight, part of the problem here was that she was still fairly hesitant to open up to anyone due to her own experience with abuse, so she was never very forceful in her signals and never said anything like "i like you". But that didn't remotely excuse the extent of my insensitivity. The last time I saw her was at graduation, where we parted on terms that seemed normal at the time, but in retrospect she seemed almost sad and defeated.
Fast forward to my senior year of college, where I meet someone from our high school, and according to what this person had heard, she is "doing great, got married." I was really happy for her, and at this point I had already started to re-assess things and realize how much I ignored and rebuffed her friendship. So I wanted to get in touch with her and express how thankful I am for her being a good friend all those years.
And man it gets even worse.
I contacted her a while later. She was happy to hear from me, but something was clearly wrong with her tone. It turns out she got married quickly out of a fear of being alone. The guy she married turned out to be a monster and was beating her (I've never been able to talk about this with other people in real life because it makes me feel so sad and guilty). Oh yeah, and she had given up starting her career in order to move across the country for his job. So when she left him, she basically had nothing, no one to turn to, and had to start over on her own.
We talked extensively, and this is the point where I learned that she liked me throughout high school, "maybe even loved [me]", but was afraid to say it outright due to fear of intimacy. We talked forever and everything was so much different since I was no longer a bitter socially-retarded teenager. I can pretty much guarantee you've never met such a sweet, sensitive, and emotionally honest person as her, but also someone who keeps getting hurt by everyone in her life (including me in my own way back then, it pains me to realize). We now talk all the time and are very interested in re-connecting in person once work settles down for a while. There may even be a happy ending to this story. But thinking about it almost cripples me when I think back on how blind and stupid I was.