I think there are lots of things that people believe could never happen to them....until it does!
Not related to Estrangement specifically but there is a connection in terms of personality types...there are some people who, however much someone gives in time, effort, caring, understanding, compromise, fairness, positivity, opportunity etc ...never give anything back, they just take. Seen it many times as a leader in the work place.
And that applies too in terms of being an AC; a partner; aMil; a SiL; a DiL...family relationships and other relationships!