When I see a person particularly an adult cannot move one from his/her first love or doing affair behind his/her spouse, I assumed he/she might has childhood trauma that makes them do such thing in their life. Throughout their childhood, they faced lack of attention from father figure for example. They tend to have affair behind they loved ones. With this they feel they get the attention they deserved. But actually such behaviour only ruin themselves slowly if they are not getting treatment for their childhood trauma. It is like a circle, if they don't treat themselves they will affect other people life overall.

In my opinion, we need to be kind to others no matter they come from different backgrounds from us. They might be a victim of childhood trauma.