My fiancee is what I would call "too nice". She's always trying to please everyone, which often leads to her taking a "grin and bear it" attitude when others expect too much of her. It doesn't matter whether she's interacting with her roommates, her co-workers, her family, or even complete strangers. What invariably happens is that they do something she doesn't like, and she just lets them.
One big one that she complains to me a lot about is her roommates not doing their fair share of cleaning. Recently, their apartment has gotten roaches. She's told them repeatedly about the roaches and reminded them about keeping things clean, but they still leave the apartment a mess and don't often clean. Last week when she mentioned that she had seen more roaches, one of her roommates told her that she should clean more. She was very upset by this because she does most of the cleaning, even when the mess isn't hers.
What I've tried
I've tried two different things, neither of which has worked. First, I tried telling her explicitly that she needs to be more assertive if she wants her situation to change. I tried telling her this about one of the issues she has at work, and she responded that she can't be assertive because she will get fired.
The second thing that I tried was offering assertive solutions. I usually suggest them in the form of a question along the lines of
Have you tried saying/doing X?
She usually hasn't tried and then offers an excuse for why my solutions won't work. Her excuses are usually about how doing whatever action I've told her to take will make the other person mad at her, and that she's trying to avoid that.
I can tell that always catering to others is taking a toll on her. I think that being assertive will help with that, but she seems to always fear that being assertive will result in retaliation. I think that if she actually tries, then the fear will go away.
How can I help her learn to be more assertive?