>be me
>have social anxiety and no true friends (though I'm working on it)
>girl I like has a crush on me and we started hanging out recently, admitted our feelings
>she still seems distant though, likely due to her relationships past
>don't want to be too desperate so I force myself not to text her all the time or bug her to hang out more than once a week like she seems to want to do

Probably a bit too much background, but what I'm getting at is that now I seem to be having these cycles of getting negative thoughts and mood where I think about my lonely situation more and more into the night until I go to sleep and have dreams where everything goes right for me (my coworkers become my good friends, my new lady says cute things to me, tells me she loves me, etc)
Then work I wake up the next day, my mood is noticably much better even though I acknowledge that it's because of a false fantastical dream

Why is my brain doing this?
Is it too protect my sanity or something?
Where can I read more about this phenomenon, I'm not sure what to Google on this specific situation