"Updike's eldest son, David, acknowleged that his father 'decided at an early age that his writing had to take precedence over his relations with real people.'" - Adam Begley in "Updike," published by Harper Collins, 2014. Here you can order it from Amazon.com.
Those who has become involved with successful writers recognize how those literary artists turn life into copy. Frequently those intimates wind up as part of that copy. Sometimes they are flattered. More often they are hurt that they have been "used." However, they should have seen it coming.
Most writers are not "people persons." Of course, as social animals writers have to interact. But they don't have to put enormous value on the quality of relationship per se. What they focus on is its utility.
A major piece of that, of course, is as copy. But a relationship can serve other necessary functions. The writer might need the sanctuary of a marriage, for example. And, if the other person enjoys association with fame then it's a fair deal. Norman Mailer's wives seemed to treasure the trip they were on.
Updike might be rare in that he was aware that he was feeding people into the creative process. He had no blind spot about being totally self-interested in his relationships.