Do you think it's okay if I propose to my girlfriend without a diamond ring?
Why do you think it would matter if you don't have one?
I'm nervous that she'll be disappointed that I'm not giving her a diamond.
There's nothing wrong with proposing to your girlfriend without giving her a diamond ring. If she loves you and wants to marry you then she won't care about the ring. I think you should be confident and not worry about not having a diamond for her.
Maybe I should buy her a diamond ring anyway.
It's up to you. But I hope that she would think that you're smart not to go into debt over an engagement ring, and care more about you than a ring.