She doesn't ask how he knows. Not only does Rey not want to hear the answer, but she figures word gets around on the network. While people are prone to being open about lamenting a lost loved one, Rey tends to prefer no one's company. She can get lost in her own head for a while, not think about it.

"Yes." She pauses, eyes fixed on the wall. "We had a... disagreement. Never got the chance to work shit out."

Between the Null attack and Rey's own cowardice, there wasn't much time left for reconciliation. Or maybe that's just another excuse.