^ I think Rachel was created from a template based on several of Bruce Wayne's girlfriends.
I'll refrain from explaining Rachel's purpose in the films again since I already did so as elaborately as I could but suffice it to say that I agree to an extent that there just wasn't enough time plot wise dedicated for a substantial romance between Rachel and Bruce but this is why I like her so much as a grounding character for Batman. In the third movie the entire sub-plot can be a romance where there was no room for one in the first two. "Batman Begins" played around with it but ultimately Batman interfered with any kind of personal happiness for Bruce. This is why both Selena and Talia are an interesting pair because as we know from the comics they kind of combine both of his worlds together which create the inner conflict as well as the external. I'm going to be really curious as to the time setting of "The Dark Knight Rises"...how much time has passed since the second film? As I said before I think Bruce will be mourning Rachel, but then again if there is a significant period of time between the two films where he has been able to recover from her loss this might be a moot point and leave it open for a natural relationship with someone to occur. I just don't want the relationship to feel forced as some of you have suggested. I too am fond of "Batman Returns" for the way it introduced and handled Selena and Bruce's relationship.