Mental illness plagues many people, and can cause a wide range of violent and self-destructive thoughts.
That said, please note that we have a strong stance on brutality and abuse, and the reference to the protagonist's thoughts about strangling his girlfriend push the boundary of what we allow in our community. You can read about our stance in this article.
You have a very good handle on how to infuse drama into a story, and make it compelling. Your story builds a strong conflict around the protagonist's inner warfare, and resolves this conflict nicely in the end.
I appreciate you bringing The Ink Well's stance on violence and brutality to my attention - it is so important for writers to thoughtfully consider the impact of portraying harmful acts, even in fiction. You make an excellent point that the reference to the protagonist's violent impulse towards his girlfriend pushes the boundary of what is acceptable. As a writer aiming to contribute positively, I will reflect carefully on this, and be more mindful of walking that line sensitively going forward. Thank you again for your perspective - it will truly help me grow. I'm glad you found the overall conflict and resolution compelling despite that misstep.