My thoughts on the ending. Strength, Weakness, uncertainty, ...

I just watched this movie yesterday and my initial thought was: Underwhelming.
But i was still cought up with its themes and characters somehow. I was still trying to solve the story.

So here are some thoughts. I dont claim to have the perfect answer or explanation. I just think it might be a piece of the puzzle.

Edward was called "Weak" by Susan and Susans mother again and again. But we never really see his weakness.
Infact, the only person that seems to be weak in this movie is Susan herself.
We only get told that Edward is an uncertain bet for the future. But do we actually see it?
Susan is from the beginning unecrtain about her work. She even sais she doesnt like what shes doing. When she confronts her mother, she doesnt show strength. She even apoligizes for bringing up her brother. But why would she apologize?

She gives up on Edward for another man. A man with money. A man with looks. But also a man with no heart or Love. He is the "no risks" guy at the cost of actual love.

At this point, susan clearly is the weak person in this story.

In the last scenes, where she is getting ready for the dinner, she leaves her ring at home, puts on a revealing dress, gets rid of the make up, in a literal sense. She realizes how fake her life actually is.
Sitting there waiting for edward, she slowly realizes that she is the weak person. He shows that he is strong enough to resist her, a strength she doesnt have. It shows her uncertainty.
It wraps perfectly that Edward does to her what she did to him, just in a slightly more twisted way. His revenge is perfect. Because its not edward that is actually performing the revenge, but Susan herself taking revenge ON herself, arranged by edward.