Reversed Psychology

However, I do like how she is so insecure about that. Girls are better, the more insecure they are. I want to see that kind of expression on their face.

In fact the more she thinks she will not make a good gf, the better wife she will be. That way she will think that she has to try harder to compensate for her shortcomings and will turn out a better wife as a result.

In contrast a girl who thinks she is perfect already, will not bother to do better. She will act spoiled and privileged as a result.

Reversed psychology.