Joanna's behavior (Some Spoilers)

We have a wife, Joanna, experiencing some marital problems with her husband who's a medical doctor. She's a psych therapist who is still pining over a deceased ex boyfriend from her youth who she fantasizes may still be alive since she believes his body was never found.

She has a married female patient who's also pining over an ex boyfriend who is described to her to be much like the her deceased ex boyfriend.

Without giving up too much of the plot, she ends up having a brief affair with her patient's ex boyfriend Clay.

The marital trouble Joanna was experiencing wasn't one sided. She was as much to blame as her husband and probably more so and it was obvious by how coldly she treated him. The husband, understanding the issue, made efforts to rectify their problems which were received coldly by her. He even went as far as to give up his position at the hospital in order for them to be able to spend more time together which basically was the root of their problem.

Joanna was an intelligent person. She wasn't insane, psychotic or a sociopath. She did have some deep psychological issues but even still she knew the difference between right and wrong.

So what does she do? She allows herself to be drawn into an affair with Clay and lies to the police to protect him. Once the dust settles, she almost allows herself to be drawn in again by him even after she decides that she wants to save her marriage. The only thing that prevented her from doing it again was a sudden suspicion she had about Clay. There was even a split second there at the end where it looked like she was going to go after him just before being surprised by the sudden arrival of her husband.

This woman's infidelity cannot be excused. She's a cheater and probably always will be. She has no morality which she proved throughout the movie in her self serving, contemptuous and deceiving behavior. Her husband would be well served by divorcing her once her true character was revealed to him and how she had conducted herself.

The script seems to point to Joanna and her husband resolving their marital problem but, in looking beyond, there will definitely be a trial in which I'm sure everything she had done will come to light. The killer's lawyer will receive discovery from the prosecution detailing her lying and detailed meetings with Clay. It will be used to challenge her credibility as a witness. Her husband will then know of her infidelity and she will have to suffer the consequences.