I just have really high standards
A way to tell someone they're not good enough without actually saying it.
I said I had high standards because I didn't want to date my annoying friend.
She asked me why I wasn't dating anyone. I said, 'High standards.' She said, 'You're just lazy.'
He asked me why I said no. I said, 'High standards.' He said, 'That's just a fancy way of saying you're not into me.'