Decide if action is required. The first thing to do is calmly and rationally think through the whole situation. Is your boss really favouring somebody unfairly? Is it proving detrimental to the morale and productivity of you and your colleagues? You have to be completely honest with yourself and be certain that it's not just because the favourite is the best at her job.[1] It's not unusual to feel jealous of someone who is having more success, so be sure you are not projecting your concerns about your slow professional progress onto someone else.