He's still attached to his dead girlfriend, what's my role?

I have been dating this guy for around 3 months and we get along very well. We have great chemistry together and i feel like i am beginning to fall in love with him. However, his former girlfriend died in a car accident. Her accident was a year ago, and though he says he is over it, he occasionally mentions it (usually when we are being intimate). I know I'm being cold, but it frustrates (and hurts) me a bit. I feel like I will always be second best to his former girlfriend, who was his first "everything". I don't want to hurt him by being insensitive to his feelings, but i'm losing my patience. I want to be with him very badly, but i don't feel like he is entirely over his former girlfriend. I feel like he still loves her, and maybe he does. I don't know what to do. Taking to him about it is difficult for me, though he encourages me to ask questions. I feel like I will never be as good as his former girlfriend.