If you don’t approve of a wedding, you need to spend some time evaluating why you feel the way you do. It may be for religious differences or concern that your loved one or friend is marrying for the wrong reasons. If you are close to the bride or groom, have an open discussion about your feelings. You may have a better understanding of their reason for marrying afterward. However, if you don’t know either of them very well, you should keep your thoughts and feelings to yourself.
Only attend the wedding if you are able to go without creating a scene. Even if it is a relationship you are sure won’t last, the person who invited you will appreciate your support. The last thing you should do is risk damaging the relationship by unnecessarily hurting the person’s feelings.