I think Angel and Cordelia grew together the way most mature romances do. Both had had their adolescent flings (okay, a two centuries plus vampire could hardly be called adolescent, but, as has been pointed out before, Buffy was probably the first female that Angel had ever been attracted to, and since her attraction was adolescent puppy love, he responded in like manner, much like any middle aged man would respond if he had had no previous experience with romance), and while they loved to look back on it later and fantasize, deep down they both knew that it was exactly that: fantasy. That's what first love almost always is in the end.
Both Angel and Cordelia had to mature before they could realize their real feelings, the kind of feelings that grow into a lasting relationship, and if the show and Cordelia had lasted a couple of years longer, we would have seen the two together in a much more mature, and no doubt intimate (they would've gotten around that curse, I have no doubt whatsoever) manner, perhaps even to the point of a marriage-like partnership. That's what mature love is.
(And before someone asks, Angel went back to Sunnydale in an attempt to recapture something that was no longer there. If Cordelia was still alive at that point, the whole "cookie dough" thing would never have taken place.