I'm never invited to stuff and my boyfriend takes 20 minutes to reply when he's with/playing with his friends..
I feel most lonely when surrounded by friends but knowing that I am not their and never will be their number one choice, knowing that I am not anybody's number one as I am no ones best friend.
When I am alone, in my squared room in the dark knowing that everyone is out there with their favorite person and I am here alone. Knowing that I will be called at least in 4th choice, knowing that I am Nobody's number one choice and never have been.
I'm surrounded by people. The anxiety takes over and every thought is how much they all secretly hate me
I feel most lonely when...
My friends talk about their relationships and I just sit there, single.
... I overhear other people discuss their experiences with their friends.
My parents leave me every weekend to go out of town for my brothers baseball tournaments.
I feel most lonely on a daily basis, when I realise that I don't have anybody at all in my life, that I can actually call a friend.
I'm in my bed and I realize that I only have one friend.
@Bigloser123
That's one more than me 
No one seems to care when I
I stay inside "to study"
@pluckyStrawberries6212
Keep up the focus on your studies.