21M, 22F Deeply in love, but our interfaith relationship realistically has no future

I'm Muslim, she's a Christian. Because of our beliefs, our families, and our own values, we both know marriage is realistically very unlikely. We've talked about it many times, and this isn't something we're ignoring.

I know we're still young, and I know that making decisions based on marriage at our age probably sounds premature. The thing is, I'm not trying to get married anytime soon. I just can't stop thinking about the future. Once I realized our paths most likely won't lead to marriage, it's become very difficult for me to simply enjoy the present without thinking about how this might eventually end.

She's the first person I've ever felt completely myself around. I can be myself and open up with her in a way I’ve never really been able to with anyone else. She’s the first person who’s made me feel safe without having to perform.

Lately, every time I feel genuinely happy with her, I get pulled back down by the same thought that when college graduation comes, or sooner or later after that, we'll have to go our separate ways.

I've been thinking that maybe college graduation would be the most reasonable time to end things. We'll both be starting a new chapter of our lives, meeting new people, building our careers, and if we truly believe marriage isn't realistic, maybe that's the fairest point for both of us to let each other move on.

But at the same time, I still want to be with her. Part of me feels like I'm rushing this decision simply because I'm afraid of how much harder it might become in the future.

I feel too emotionally involved to look at this objectively anymore, and I'd really appreciate outside perspectives. If you were in my shoes, what would you do from here?

TL;DR: 21M dating a 22F in an interfaith relationship with no realistic path to marriage. I still deeply love her, but I'm considering ending things around graduation and can't tell whether I'm being realistic or just afraid of future pain.