Sinfidelity (2020)

A drunk man named Tyler, carries a knife in his pocket. He goes to a rollerskating rink and stalks a grown-ass woman. She tries to skate away but is attacked. He takes her photo and calls her a liar, then he stabs the woman and takes pictures of her dead body. Cut to a fancy party thrown by an entrepreneur named Greg.

His wife, Angela, loads up on wine and talks to a photographer named Franco. He takes her photo while she holds wine. (She is in the wine business. ) Angela checks on her child that she left with a woman with a gun and heads back to the party. At the party, she finds Greg canoodling with his assistant, Lisa. Angela is jealous. Angela sees text on her husband's phone sent by Lisa, quoting "it is bad to hide this from your wife, we should tell her" etc. Franco stops by Angela's house to give her a photo he developed of her overnight. Claire, Angela's BFF, learns about the assistant and tells her friend that he is probably cheating. Greg has been unfaithful in the past. Instead of getting a divorce, Claire suggests Angela has an affair of her own. She packs an overnight bag, leaves her daughter with the sitter (Janie), and meets Franco. Angela tells Franco about her husband's previous affair. He tells her that she deserves love and shares his experience with cheating spouses. Then a hoedown happens, and Angela and Franco kiss. Franco cries and overshares about his "Niece" who was murdered fifteen years ago. They have sex, and he tells her that she shouldn't go back to Greg. Then he says, "You have my heart if you want it. " The next morning, Angela finds photos of the "niece's" dead body. He catches her and gets very defensive. Angela comes home and screams at Greg for cheating on her with the new secretary Lisa. Greg explains that she misunderstood everything and is taking Angela on a trip to Italy for their anniversary. Lisa was helping him book the travel and jewelry. He promises he is faithful, which makes Angela regret her life choices even more. After taking a sad shower, Angela tells Franco that he needs to stop contacting her because she is staying with her husband. Franco, of course, doesn't leave Angela alone. He stalks her and follows the couple on their anniversary dinner. He bugs Angela and listens to Greg's conversations while he develops photos of Angela in his darkroom. He has video surveillance too. Then he picks up Vivian (the daughter) from school and confronts Angela in her home. He forces her to admit that she cheated and is convinced that she is still in love with him. Then he throws a rock through a window and injures the dog. Greg gets an email and immediately pours himself a glass of whiskey. Something is wrong with the numbers, and Greg's business is in trouble and THE MERGER. Angela goes to the police and tells them about Franco. Then she goes back to her BFF Claire to get more advice. Angela realizes that Franco bugged her house and tapes over all her device's cameras. Then she makes a romantic dinner for Greg, and Franco crashes the party. Franco forces himself on Angela and tells her to stop fighting her. She finally comes clean and tells Greg about her SINFIDELITY. He screams at her. Meanwhile, Claire is in a bar drinking martinis and meets Franco. (Only she doesn't know it is him. ) They hook up. Afterward, Claire takes a picture of Franco while he is sleeping and sends it to Angela. Angela tries to warn her friend, but Claire thinks it is a joke. Then she is attacked in the darkroom and ties to the bed. Angela calls the police, and they don't seem concerned at all. Angela gets a gun from a lockbox and takes matters into her own hands. She breaks into the house and finds Claire stabbed to death. There is a note that says Franco has Angela's daughter. Franco listens to records and drinks red wine while holding a knife in Angela's house. Angela shoots him in the back and he runs away. Angela demands to know where her daughter is. Franco takes pictures of her and she begs him to give her back her daughter. She smashes him in the head with a wine bottle and tries to shoot him, but is out of bullets. Angela reloads and shoots Franco. She finds Greg tied up and as she is untying him, Franco rises again. They struggle and Angela tumbles down the stairs. Greg gets the gun and kills Franco. The couple head to Italy. (thanks to lifetimeuncorked)