There is a big difference in being nice and being a pushover. My opinion on the differences are;
Pushover -
Smothering types who shower the girl with gifts
Always opening doors
Letting her make most if not all of the decisions
Asking permission to do anything that doesn't involve her
Nice -
Giving compliments when they are needed ie:new outfit, hair style, etc
Performing duties that a woman normally would be unable to do ie: picking up something heavy, killing bugs, etc You can still be nice without having to be at her beck and call
Hearing her side to an issue/idea, giving your side/idea, then agree (NOT COMPROMISE) on something that you both would enjoy.
If it's a woman, not a girl, and knowing that you both don't have something already planned, simply saying "I'm going out with friends tonight" should be the end of it. Tell her where you're thinking about going is fine. None of that "is it okay if I go out with so and so". You're a fucking adult and don't need permission.