<human>: Can you provide a brief rundown of the text in within 3 sentences?

Whenever there'a a group project I'm the one that's picked last, when my friends decide to go out they often forget me(I assume, maybe they flat out don't invite me), and in conversations I'm always the one that is slightly out of the circle. I don't understand why that is, I'm friendly with everyone, I'm not ugly or whatever, I can keep a conversation going and I make the group laugh etc, but still I know that they wouldn't mind if I weren't there, they wouldn't feel my absence. 
There's also this girl that is in my group of friends, she was studying abroad and came back for a week, we've talked a ton when she was abroad but she didn't tell me she was here for a week and went out with the group, no one invited me. I only found out when photos popped out online, group photos or friends I considered pretty close to me, smiling and having fun without me.
<bot>: I feel excluded and I dont know why because I think I'm sociable, but the girl I like came back for abroad country and went out with my friends without telling me even tho I was looking forward for this .