You never really know what goes on between people. I still don't know what my sister's relationship is like with her S.O.

When you see a group of people who know each other...can you catch the undercurrents and different emotions roving amoungst the group? If someone is having an illicit affair...can you gauge who that might be? How are you at interpreting interpersonal relationships...when you meet a husband and wife..can you 'see' how fond they are?