The general etiquette is that if you are not invited to a wedding, you are not obligated to give a wedding gift. Wedding gifts are typically given as a gesture of congratulations and support for the newlyweds as they embark on their life together. Since you were not invited to the wedding, it is reasonable to assume that the couple may not expect a gift from you.
However, there are a few exceptions or special circumstances to consider:
Close Relationship: If you have a very close relationship with the couple, and you genuinely want to celebrate their union and show your happiness for them, you may still choose to give them a gift. In such cases, it's more about your personal connection with the couple rather than adhering to traditional etiquette.
Cultural or Regional Norms: In some cultures or regions, it is customary to give wedding gifts even if you haven't been invited to the wedding. If you are aware of such traditions, you might consider giving a small gift as a sign of goodwill.
Wedding Announcement: If you received a wedding announcement (a formal notification of the wedding) rather than an invitation, it is not expected that you send a gift. Wedding announcements are often sent to inform friends and family of the marriage after the event has taken place.
Professional Relationship: If you have a professional relationship with one of the individuals getting married (e.g., coworker, supervisor, business partner), you might decide to give a modest gift as a professional courtesy, but this is entirely optional.
In any case, the decision to give a gift is entirely up to you, and you should feel comfortable with your choice. Remember, the couple will likely understand and respect your decision either way.