Cynicism & Close Relationships:

Randolph M. Nesse:

"But those who say 'Most people are out for themselves, but what else can you expect?' tend to have problems with close relationships. 

Such beliefs are self-sustaining. People capable of trust pair up with similar others and are likely to have relationships that confirm their positive expectations. They shy away from cynical types. So, people who think that others are self-interested tend to have untrusting and often untrustworthy associates who confirm their worldviews."