Hmm. Interesting. In Advent Children, I didn't see that big of a difference. She knew Cloud was effectively running away from his problems, and pretty much let him do it until the earth was threatened. Even then, Marlene seems to have had the bigger impact on him changing his ways. At least, that was how I saw it. I could be wrong.

With Aerith, I actually saw her being able to make Cloud question himself. Have you ever known someone that could be wise, but appear to be slightly ditzy at the exact same time? It kind of provides someone ego-intensive (like Cloud) as a way to say that he figured everything out "on his own" without actually solving it on his own. She did it in Advent Children.

But would the relationship last? Nah, I don't think so. So we're definitely agreed on that.