Search Results: adding a girl on facebook i don't know

We're both 18. More info below the question!

I was at an anime con and met her there and chatted with her briefly for 10 seconds. By her appearence she looked too young so i didn't think much of her. Later I was looking at pictures of the con on instagram and found her and noticed she's actually 18. I DMed her and we started talking.

Atm, I've only known her for about 4 days. On the first day of DMing her, she was giving lengthy responses and responding to every thing i said. i asked for her number the next day over DM and she didn't hesitate at all. that second day she continued to give length responses and respond to every little thing. i hinted at hanging out with her at future anime cons/outside of cons and she sorta seemed interested?

Things started to slow down on the third day, i actually had to steer the conversation a bit to keep her responding. she didn't talk much at all the third day and i straight up asked her if everything is okay and she said everything was fine. Now here's the funny thing. I'm not sure if this is a compliment or not, but randomly after not hearing from her for 3 hours (and again she was slow at talking that whole day) her friend adds me on facebook and starts asking me funny/odd questions about the girl im talking to. i messaged the girl if she knew anything about this and she was like "haha we were just pranking you. dont worry". We continued to talk a bit as normal and on the fourth day we also talk a bit as normal.

On the fourth day something random and odd happened. her friend again messaged me saying "___ doesn't LIKE YOU" and i texted the girl and was like "hey your friend said you dont like me. if you wanna stop talking its all good" and she said "ignore him" and i said "you sure? im honestly not gonna be offended. I've delt with people that say they're your friends but secretly not. honesty is good ya know?" and she replied "It's cool, i just dont talk to people in general, only a select few. He likes to mess w/ people"