I need help with my relationship

I 23(m) am in a 4yr relationship with gf, and I really don’t wanna lose her. We are both lukewarm Christians but I find myself wanting or feeling like GOD is calling me more. We had a conversation about this about this a year ago, about getting closer to GOD. At that time I was reading about being unequally yoked, and that possibility of us not being spiritually aligned by the time of marriage was super concerning to me. I don’t know if we will be on that same timing by the time we get to marriage age. I was and still am developing severe panic attacks, because the thought of losing her was too much to bear on my heart. This woman has brought me out of a bad depression and has loved me more than I have felt from my family, and the thought of her being gone is truly terrifying. She is my number one supporter in everything i do. She has made me a better man in every way possible. We have only had one argument in 4 years. But from everything that i read, it makes me feel like I’m going to hell if i don’t break up with her, and this feeling is disturbing my mental. And ik the lord is my father, but idk if im following him bc i don’t wanna go to hell, or for a relationship with him. If I knew that there was no suffering people who didn’t enter heaven then Idk if I would be as devoted. If nothing existed after death, then breaking up with her would be the worst decision of my life.