Horror thriller I can't remember the title

I watched this when I was 10 and we rented the movie from blockbusters so I can’t go through the back catalogue.
The film was on DVD so it isn’t a TV film, and it’s about a light-haired, possibly blonde, woman being stalked. Spoilers but she thinks it’s her new boyfriend in her life but it turns out to be her co-worker or something. The most vivid scene i remember is the flashback to her going to a mental hospital after slitting her wrists and a boy younger than her having a crush on her. He ends up stopping her from hanging herself, and then she gets transferred I think. The twist is the coworker(?)is the little boy that saved her, he’s pissed because she doesn’t fall in love with him when they meet again as adults so he attempts to hang her where she tried to hang herself years ago. She gets saved I believe and the whole film had a very dark colour palette so I’d say it was one of those 1990s-2000s woman being stalked thrillers, which has made it very difficult to find on Google. It’s not The Caller (2011), Possession (2009), or any film that bases itself in an asylum because that’s only in the flashback, she’s not there anymore.