psychology is everywhere

There must be sth happened today.
She saw that her classmate
and she was quite nervous.
she wanted to say sth and would have a nice talk with him.
but today still a normal day
there is no something miracle
when the lecture is over
evertbody started to get out of sala
he was standing near the exit
she passed him and said "hi"
it should be"bye" or ....
but nerver "hi"
it was so strange she thouht
she got upset
she didn't see anything special from his eyesight
she really means nothing to him
yes it is true
in his eyes,she 's  just a classmate
and nothing to say with

what is the situation now
a sort of psychology?
i don't know