Nah this is not her being punitive because she's mad, or something she'll do again when she's mad. This is her drawing a line in the sand: marry me or be gone so I can find a Christian man who will marry me. Like I said earlier, somebody (pastor, parents, grandma, etc) got her feeling guilty about living in sin with you.
I'd bounce. I have zero interest in religious women.
Dude already said they weren't trying to get married anytime soon so

at the end of the day, its already a toxic relationship that needs to end.