Ark Two was designed and built as a shelter meant to allow people to survive the harshest catastrophes imaginable. That means that space inside the shelter is at a premium, and things like keeping families together take second priority to comfortably housing as many people as possible.
For this reason, sleeping quarters at the shelter will be split into Men’s and Women’s—which means that families won’t be able to share a living space. But the way Bruce explains it, it’s for a good cause.