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.
Dream dictionary: attending a friends wedding dream meanings
…When a woman dreams that she marries an elderly man, it suggests that she’ll soon have several problems, including a painful illness. If during that marriage the groom has an angry attitude, it indicates trouble with friends for who you had great esteem. Dreaming about a marriage suggests upcoming good news and joys, but when a woman marries and those attending the ceremony appear dressed in black, it suggests that the dreamer will suffer disappointments and sorrows. In some cases it indicates death of a beloved one, either a relative or friend. When the dreamer sees him or her filling the application to get married then it symbolizes bad news. If the dreamer is in a wedding party and behaves as a relative of the bride and groom, it symbolizes that other people estimate him/her, and so his/her business affairs will prosper. If a misfortune occurs during the marriage…
…hair in a dream, it means that he will cover up the loss of his ablution during prayers or during his reading of the Holy Qur’an or during other ritual occasions where he is required to have ablution before proceeding. It could also mean that he cares little about attending his prayers. As for women, dyeing means happiness, new clothing, receiving gold, or a wedding celebration. If the dye exceeds the required surface of the hands or the feet in the dream, it means being struck with fear and worries caused by one’s business or friends. If a man sees himself in a dream dyeing his hair or beard with other than henna, it means that he will suffer from what he fears most. Dyeing or suppressing one’s feelings for a sick person means recovering from his ailment. Dyeing one’s hair black in a dream means hiding one’s bad conditions,…