A wearable of some form (bracelet, necklace, other jewelry, clothing item) glows when you have made contact with your, and your wearable’s counterpart.
This is a literal take on the more emotional response of ‘lighting up’ as a person when you are in contact with a person whom you have strong feelings for.
It seems facetious in some imagined scenarios, but could be a subtle exposure and reinforcement of feelings couples have for each other.