Best friend approval: important or not?

I've always been trying to decide whether my best friend approving of my boyfriend matters to me.

I mean, I've had several boyfriends. She's only ever disapproved of two. One of those was the best boyfriend I have ever had; and the other is my current one.

I just can't decide whether her approval actually means anything to me or not. I mean, I stayed dating the first guy she disapproved of for ages. Although, she only disapproved of him because she thought he wasn't smart enough for me.
Which is BS, by the way. He is intelligent. Just in a different way to me.

This new guy, that she disapproves of, I'm starting to have second-thoughts about. And I'm trying to figure out if I'm thinking those kinda thoughts because she doesn't approve. Because I'm slightly determined not to let what other people think affect me.
It didn't seem to affect me before, but maybe I was just more determined then.

Anyway. My point is, do you think best friend approval is important? And does it alter your own opinion, whether you want it to or not?