I know for a fact that I cannot answer why most women (and some men) feel the need to "fix" their partners/friends/lovers, what have you, I can only answer what I feel and know.
I believe firmly that a person can only change for themselves, not because someone wants them to...changing for others means (in my mind) that you only put a veneer on the surface of "you" and veneer can warp if it's not taken care of. If a person is not happy with themselves, then they can never be happy enough to share their with another.
RE: A Fluffy subject - Who is your favoriate comedian(s)?
Here's another: