Is it possible to get married in Mount & Blade sandbox mode?

Yes. According to the relevant information of "Mount and Blade", the steps for getting married in the sandbox mode of "Mount and Blade" are:

1. First, make preliminary preparations and find an NPC to learn poetry.

2. Next, go to your father-in-law, meet your fiancée, propose marriage to your father, the task bar will appear, and complete the task according to the requirements.

3. Finally, give the bride price and wait for the messenger to come to let the player attend the wedding.