always be objective, never let your feelings get in the way when making important decisions, step one step back and look at the situation from somebody else's perspective.
here's an example, let's say a woman is constantly checking your phone, asking about other women, accusing u of cheating, puttong u down etc in your eyes she's probably just a tad jealous and seems normal to you because she's your girlfriend, but if that's the case with somebody else's wife or GF you probably see that woman as an over jealous annoying bitch