The most likely intepretation is that he's suggesting that he prefers for married people to not work with each other on a task. It can create command structure issues, and can introduce risk in that married couples sometimes prioritize each other over the overall team.
In actuality, of course, based on his other actions during the episode, such as convincing Wesley to not do additional scans, this is more likely simply a way to get Wesley to doubt himself, as a power play.
On a side note, the married couple probably is Hildebrant and Alans, both because they're listed together in the description of scientists and because, as noted in this Teknobabble discussion of the episode, they start to finish each others' sentences, something common in couples:
HILDEBRANDT: The ore is forming generator strata.
ALANS: Which creates a piezoelectric effect.
PICARD: In plain English, you're saying the dilithium is causing the geological catastrophe.
ALANS: Right, the crystals take the natural radiant heat of the planet
HILDEBRANDT: Focus it, and turn it into mechanical energy.
ALANS: Which increases tectonic stresses
HILDEBRANDT: That tear the planet apart.
It is possible that he was referring to "married teams" in a more abstract manner, breaking up teams that have worked extensively with each other without any actual matrimony, which is often invoked for much the same reason (tendency of said team members to prioritize each other over the mission, tendency to back each other up right or wrong).