Is I'm lacking something?

So I'm 35M living in India and my girlfriend 36F is really kind, we been into 2 years of relationship and everything is going quite normal suddenly so talked about her previous relationship in middle of our conversation that how he used to be toxic with her and got physical many times with him and beside I just quite listening, her ex cheated on many times and her ex girlfriend is kind of supportive then slowing she called by her name and I saw the picture of her ex girlfriend, the fun part is my girlfriend's ex girlfriend is my colleague and I had a crush on him but never approach or initiate to propose her. Been an introvert i missed many opportunities which I regret the most now, and sometimes i feel myself that I can't provide much effort that my girlfriend need to be. There was a time when the starting attraction phase is fading slowing then you both are well mature to understand their behaviour and yet she can't understand me properly or my nature and feels like I'm still a Stanger for her. Before you judge me I never harsh on her, yet still feels like a gap. Sometimes i also hesitate to ask her for intimation (sex). Like honestly i don't know how to approach a girl for sex.