My girlfriend who is bipolar has those moments. In fact she's dealing with it right now when it comes to our relationship. I am one of the first nice guys she's been with and she feels like things are just too good to be true. She's also afraid she's going to mess it up. I will share with you the same thing I try telling her. Live in the moment and try not to think things are too good to be true. You deserve the good things! I know it's hard to believe sometimes but it's true!