MC has projective emotional luck ie anyone they have feelings for gets lucky.
The luck can be good or bad depending on whether the triggering emotion is positive or negative.
The triggering emotion has to be of a certain intensity and duration before it triggers the projective luck (in other words basic everyday feelings like irritation won't trigger the projective luck).
MC's projective luck can only affect those they have met and interacted with in a personal manner (so wouldn't affect say a political candidate no matter how despised unless they have previously met and personally interacted with that candidate).
Many different storylines possible based on these guidelines especially if you add knowledge of the ability, both personal (MC knowing) or otherwise (MC ignorant of their ability but others suspect/know based on observation/history and could use that knowledge to manipulate the MC's feelings toward others for their benefit/gain/enjoyment).