Overhearing something was only a small part of it, but I think the story fits in with the others here. It's kinda the reason why I'm so light on friends and feel little to no need to get more.

So, in my younger years, I've been somewhat of a shy person, contacting other people was quite hard. The main group of friends I had during primary school were due to the connections of my parents. I could get along okay with them, birthday parties and stuff. This group transitioned to secondary school. There, things got awkward. I noticed them contacting me less and less, and one time when I was walking by (without them noticing me), they started talking crap about me, how I didn't fit in etc. This kinda hurt, but I went on anyways. However, some weeks later I wanted to join them during lunch break, but they started teasing me to go somewhere else. In a laughing way. I smiled painfully and sat down, but they kept continuing. After a while it became clear to me that, even though they did it in a teasing manner, they were serious. So I left and lunched on my own. Their intent became even clearer when they stopped contacting me completely and never said anything anymore. In a few weeks at best, I went from having a decent group of friends to being alone in secondary school. I felt even worse during one of the school parties, where a girl was asking guys randomly to kiss with a friend of her, until she came to me and simply said "no she ain't that desperate"... Because I wasn't fluid in insults and the likes, I resorted to my size and started getting physical with those that made fun of me. I got detention a few times, but luckily nothing serious. At least they stopped teasing me...

After a long time I found another group to hang out with, mainly through the connection of 1 guy (pretty much my best friend since then). We hanged out during breaks and sometimes had a party. Things changed when that 1 guy and I got in a serious argument (I think our ego's clashes, but I don't remember the details), almost getting physical, until we split. Shortly afterwards, the others in the group started to ignore me and even refused to keep me in classproject groups. I even got an email from one of them, telling me they no longer want to work with me "because of what I did to Guy 1". They never spoke to me, asked me anything, nothing. Again I was pushed out and left with the idea that none of my friends were real friends.

Luckily, Guy 1 and I overcame our argument and been very, very close buddies since then. We left those other guys once Guy 1 discovered they were going full retard in ways he didn't agree with. Since then that shitgirl tried to add me through social media, which I refused of course. Since I'm getting older and have had to speak publicly more, I lost my social anxiety and after I crossed her in public transit once, I gave her the most relieving, degenerative speech I have ever given, with the entire train to hear it.

So yeah, I have few friends. But those I have, they are real, they are the ones who kept with me through shitty times and that has become something I value greatly.