What does "friendly" mean?

[The Land]

I'm now "friendly" with the main faction in a system. What does this actually mean? I can't see any effect really!

 

[kylania]

It means you can date their sister.

 

[EAGLE 5]

From a practical standpoint you will start getting better paying missions and more often from your newfound friends.

 

[oomwat]

It's the stage before Allied - where you get the really juicy missions