"I guess the online gaming community isn't a good place to find friends if people are going to be like this."
First of all just because a handful of girls don't want to talk to you doesn't mean the entire community is the same, really now. That first was a pretty douche-y thing to say, but given that it's the internet it will be overlooked.
"Adults don't do that in the real world"
"At least 18"
Son just because they're 18 doesn't mean that their switches have been flipped and are instantly acting like they're in their 30s, it's "eigh-TEEN" not even out of the teens yet, come on. (If you think all adults "in the real world" don't talk down to you or do any of the above that you whined about then you're in for a surprise.)
"...I add on league and twitch..."
Before everything, as you have said in the below, you aren't thirsty or not everyone is like that (even though you did the exact opposite of the "not everyone is like that" argument by saying "I guess the online gaming community isn't a good place to find friends if people are going to be like this.") Also the fact that YOU added them, not the other way around, and from what I can tell: not even after playing a match with or against them, sounds quite thirsty. More often than not, most people on twitch won't play with you or talk because they're busy with friends they already have, making friends isn't a one sided thing, they have to want to be friends too.
"I'd much rather talk to someone who wants to develop a friendship with me, not to be used like α tissue paper and thrown αwαy. "
That's your own fault, if you add someone out of the blue (not even after a match) then more than likely they'll either decline, or accept out of being nice in general, but that doesnt mean that once you're on the friends list you click and become best friends, or that they're obliged to talk to you everytime, you also have to wonder if they really want to be friends with you. Also how, pray tell did they use you? Throw you away? that's a bit far fetched, and if you bought them rp or some other dumb thing like that without really knowing them, well, that's your fault.
"...then unfriend me so you cαn stop wαsting my time."
You must realize by now if I had all the time in the world I would pick your post apart.
From my point of view, and I'm sure most would agree with me: you're wasting their time. This ties in to my above statement where they aren't obliged to talk to you, and if they ignore you they're probably doing or talking to someone of more importance than some random boy who added them. (You must realize that a good chunk of friends made in league are ones added after matches, other wise is just kinda creepy.)
"This hαppens αt leαst 10 times in α spαn of α couple of months."
Well if you keep LOOKING SPECIFICALLY for girls then yes it will happen, and that makes you thirsty, literally just play the game for god's sake, make friends that way, and mind you there are nice blokes out there too. (The fact that it's just girls is telling of thirstiness.)
If you want to solely make friends (outside of league, not teammates or play mates) then go on tinder or some other site and do it there. But if you are going to whine about girls YOU added on league for seemingly no reason, then kindly stop.
(The same goes for males you add, if you add any, usually if they don't add you or you don't add them AFTER A MATCH, it's a sign they don't want to be friends.)
Now go and apply what you've learned to yourself.
Happy playing and may solo q be ever in your favor.