What does a girl mean when she says she's "an easy person to keep happy"? 35ish, mostly adventuress, with hints of materialista.

If you haven't read PFP, "adventuress" is a heuristic to describe a woman who is strongly driven by male validation. A materialista should be self-explanatory. No woman is totally one or the other of these, and it can even change depending on her circumstances. Think of them as if they were stats in a video game.