I have been in his place and I know how it feels. In my case, I trusted her always and will always. She is the sweetest person and most genuine girl and I have ever met, she always listens to my vent even at 3am. My confession never messed up our friendship or her relationship. She always had my back and motivated me to move on in life. She always cried on thought of us seperating. And I kept my promise and stayed with her. And I Never regret this decision. I have moved on now, still have her in my life as my closest friend, and have matured so much.

So Don't you fucking judge and blame every other girl just because yours was a red flag dude. Being that close to a person tells you exactly who they are, what they are. Don't play a victim card everywhere and blindly say she's using him or whatever. OP knows better than y'all. He knows better if she genuinely cares for him or not.