Left My Non-Muslim Partner and Feeling Conflicted

As a Muslim woman (24), I was in a relationship with a man (27) for a few months. At first, I thought he was Muslim since we live in a predominantly Muslim country, but later he shared he wasn't sure about faith or Allah's existence. I tried to be understanding, advised him to research more, and figured it was okay to have questions and learn. We sort of dropped the topic and just focused on our daily lives and careers... But then, one day, it started bugging me again, so I brought it up to see how his exploration was going. He said that when he talked about making an effort, he meant he'd look into it after marriage if we ever got married, but he had no plans to change his beliefs now and was content as is. So I ended things because it felt pointless to try changing his mind, and I don't have enough knowledge for deep debates. Honestly, he was a really great guy-respectful, kind to others, didn't drink or do anything haram, and even fasted sometimes. But deep down, he wasn't convinced about Islam and didn't pray. The breakup has left me pretty down. I keep wondering if I should've tried harder or waited longer. Maybe Allah put me in his path to guide him? Maybe with more time, he would've changed. I've also been feeling confused about deen-why would someone so good face eternal punishment just for not believing? Why can't I marry him, even though he made me so happy? Has anyone else gone through something like this? Do you think I should reach out again and encourage him to research and reconsider? Any advice would be really appreciated, insha'Allah.