The person standing next to you at the altar (aside from your fiancé) is meant to be the one who is closest, knows you best and whose friendship is most cherished above all others. No rule says it must be a woman and, while often expected by guests, if that person for you is a male, there’s nothing wrong with him taking on the role. However, typically, his duties will differ in some ways than that of a Maid of Honor.
While he likely won’t be at your floral appointments or help you pick out table runners, your Man of Honor can still help you decorate and his handyman skills may be an added bonus. While he may not share the enthusiasm a girlfriend would for every little detail, he certainly will provide the listening ear and offer assistance which is the most important part of anyone in the coveted position.
Additionally, gender is no issue when it comes to rehearsal roles. Man or woman, the duties are primarily to provide you with a practice bouquet, make sure everyone shows up on time, is paying attention and to give a toast (if appropriate).
The day of is where things typically get a little bit different. Because he won’t be cinching your corset or pinning on your veil doesn’t mean he has to be excluded from the festivities. Put him in charge of grabbing anything for emergencies that may arise and getting food and drinks that he can enjoy with you and the ladies as you all relax and prepare.
Ideally, your Man of Honor will wear something that matches your bridesmaids but, keep in mind that he will probably be in some photos with just the guys too. Electing for something that meets in the middle is the safest and best way to go.
No matter who you choose to stand directly next to you during your ceremony, the selection should be based upon your history, trust and value rather than be constrained by gender or the expectations of what is considered “normal” or “acceptable.”