^ I agree that the series doesn't portray them that way because it would insult the audience. That's why I said "if we're being realistic". Obviously the show can't be. But, a 2000 year old being is to a 20 year old as a 30 year old is to a 4 month old baby!
I mean, maybe? It's not like anyone's ever lived that long.

It's entirely possible that there may be a point where emotional maturity just plateaus -- where you just hit a certain age and there's really no more emotional growth, just a perpetuation of whatever personality has developed. I mean, looking at real life (where the oldest recorded human being was, IIRC, 125 at time of death), is there a meaningful difference in emotional maturity between, say, a 120-year-old and a 60-year-old? Apart from the issues caused by the elder party's decreased physical acuity, is there a meaningful difference between the relationship between a 60-year-old and a 25-year-old, and the relationship between a 120-year-old and a 25-year-old?
My suspicion would be that at a certain point, the relationship between someone very old and someone younger simply stops growing, that the numerical age gap ceases to be proportional to the emotional age gap. That, at a certain point, being older just registers as being older, and the exact age itself ceases to matter.