Maintaining social relationships is very intellectually demanding task. Animals that maintain social societies have larger brains than individualistic cousin species, in general. It is called the social brain hypothesis. Hyper intelligent people might tend to be less able to maintain relationships because they are too far outside the norm, not because they are smarter, per se. I would say that people with intellects much lower than the norm also have that problem.

Or it could be that, with our current hardware, brains that are hyper intelligent are in some way cannibalizing brain power that is “normally” used for processing social dynamics. In that sense, if we increased the processing power, people could have sufficient equipment to run both.