Too nice?

I wonder sometimes if I'm just too nice. I know that nice is generally a good thing, but being too nice can have its problems too. You get taken advantage of and treated like crap by some people because they know that you aren't going to do a damn thing about it, perhaps even apologize to them for the pleasure.

Two examples:

There is this person, let's call her A1. A1 was a nice girl who seemed to have an interest in me and led me on for months. After a while, however, A1 started to get flaky. She would start to blow me off, call and text less frequently and eventually stop communicating with me at all. It didn't matter to her what I really thought. She knew that she could pretty much do whatever she wanted and would get away with it because I would always be the nice guy and forgive her, regardless of whatever mean and deceitful action she took.

Next: person A2. I've known A2 for a long time and we usually get along fairly well. But, A2 is a bit, shall we say, temperamental. It's like walking on eggshells. No matter how innocent the remark, odds are 50-50 that she will take it the wrong way and blow up at you, or even stop talking to you for a time. Whatever happened to giving friends the benefit of the doubt? I've put up with this nonsense for years and have often times even flat out apologized for offending her. But I'm pretty damn sick of apologizing..... and sick of her crap too.

There's a difference between being nice and being a doormat anymore.