As much as I enjoyed this film, I also found it highly unsettling, both in the unfulfilled way that we're supposed to feel at the end and in Eva's construction. The way that Eva is built up and made into such a shining and interesting character, only to be reduced to a plot device or catalyst for the upheaval in Bruno's life was (I'm not going to lie) very disappointing. For some reason, her behavior at the end just didn't feel like something Eva, the character the filmmakers constructed and made us believe in, would do. Perhaps in that way, it was the ultimate betrayal on Eva's part, one that tricks the audience as well as the main character. Even so, I less resent the character for leaving and more the [male] directors for deciding to move the narrative in that direction. I suppose it had to happen in order to drive the male-centered narrative about the trusting, helpless, honest Bruno who takes in this poor prostitute and gives her a new life, only to find out that she's an ungrateful harlot.
I'm not salty at all.
All sarcasm aside, her character was extraordinarily interesting and complex character, qualities which are not usually gifted to women in mainstream cinema. The process of identification is made more easily because she isn't classically beautiful, she also easily allows us to pity her because of her situation, which makes us (the audience) want to comfort her. That being said, she is the symbol of harmful human interaction, because she deceptively brings all of the pain into Bruno's life that we see. We, the audience, is coded to feel betrayed in the end, because Bruno is the protagonist.
Hopefully that made sense. If not, feel free to ask for clarification.