What kinds of hardships affect people's loyalty

People's loyalties are affected by hardships in many ways. The actual test of loyalty is when going through hardships. In hard times when it becomes difficult to take care of even yourself that is the time when true nature of people is revealed. For example when you marry someone both make promises to stay together in hardships but then in those hard times someone cheats on other or if one is going through tough time the other might break the vows just because he/she cannot go through that phase with their partner. Another way is that people are forced to do something in a certain situation which by nature they detest and would never do.