Caught in a secret bond, longing to break free

Assalamu Alaikum. I hardly know where to begin. I became close friends with a guy (which I know isn’t right Islamically) and eventually we told each other about our feelings. That’s how it started. I care for him deeply-he’s incredibly kind, understanding, generous, and always there for me. Truly, he’s a great person. But, in the end, this connection isn’t halal. We’ve talked about stepping back to work on our faith, yet we always end up saying we’ll just keep a little distance but still stay in touch. I’m already so attached. He doesn’t seem as bothered by the sin as I am. I’m not even sure if he should be my future husband, because something feels off. At first, my heart warned me against this. We’re both still studying, and I’m not ready for marriage. He once admitted he wasn’t fully certain about marrying me, though he later changed his words. I’m stuck between missing him all the time and feeling this heavy guilt. If anyone has any advice, please guide me.