If you get married to a partner from another EU Member State, you should take a few things into account.

Before marriage:

Find out which legislation applies to the marriage. After all, this has major consequences for your rights and obligations as a married partner. If you are getting married outside of Belgium, ask the authorities of both countries what to do so that your marriage is in force in both countries. Sometimes the marriage has to be registered with different authorities.

After marriage:

A marriage is recognised in all EU Member States (this does not apply to same-sex marriages, which are not yet EU-wide recognized). If you are getting married outside of Belgium, also register your marriage at the Belgian embassy or consulate.

Source:

https://europa.eu/youreurope/citizens/family/couple/marriage/index_nl.htm