I have some thoughts about this, so excuse me if i ramble a bit.
When it comes to crowleys human blood arc and the feelings he's experiencing, we actually got to see a glimpse of what's going on on his head during the curch scene at the end of season 8.
"I just want to be loved. I deserve to be loved."
He just wants to be loved really, but also he never experienced what it means to be shown genuine love and affection, so everytime anyone tries to get too close emotionally, he immediately gets uncomfortable. For example when Gavin tries to hug him at the end of season 9, when Bobby thanks him for healing his legs in season 6, when that random girl hugs him and thanks him in season 12.
He can deal with surface level affection, where it's always kinda put as an sarcastic joke, but he doesnt know how to handle genuine affection. Even though he yearns for that.
He wants a deep connection with someone, we see that with the whole demon dean thing and also when rowena comes back into his life and he chooses to still keep her around even though he knows that she certainly doesn't have his best interests in mind.
He basically tries to connect with people on an emotional level that he knows aren't interested in connecting with him.
I saw a really good in depth character study post on him here on tumblr.
It has 9 parts and I'd recommend you read it all, its really well thought through.