To dream that you are the groomsman in someones wedding, means that you feel appreciated by your friends. If you are attending the wedding in your waking life, it shows that you are worried of being a groomsman. If you so do not feel happy while being a groomsman, it shows that you are not happy about someones relationships as well.
Groomsman dream meaning
Read more about dreaming of Groomsman in other dream meanings interpretations.