Seriously?
He was late to work one morning because he overslept at the apartment of a woman he'd fallen in love with and got laid for the first time in...what, forever?
That's not exactly the beginnings of a morbid spiral.
Oh, and he insisted on his friends meeting Laura.
He was a little carried away with the fantasy...and when its limitations became apparent to him, he stopped.
Gordon wasn't "obsessed" and wasn't having mental health issues.*
As for Laura...okay, Laura's been dead for four hundred years. We never meet her; we meet her own notion of who she was and how she chose to present herself to others.** It's not her story, it's a story about Gordon getting wrapped up in her story.
*Yes, I get that as sensitive human beings we now agree that all disappointment, frustration and hardship is traumatic and leads to severe mental health issues.
**Texts aren't journals, diaries, or notes to oneself; they're presentation to others.