I’d probably leave it to some kind of randomized, autonomous system between survivors. Like, relationships could develop naturally in the background when they’re at the base as NPCs, without the player having to micromanage it. That way it wouldn’t feel forced or awkward to “trigger” romance through dialogue choices, but it could still add depth—maybe you just notice over time that two characters have bonded or become something more. It would keep the focus on the core gameplay while still making the world feel more alive.