Getting married with a tourist visa

Given the time constraints it is possible but improbable. Also you need to establish residency and that isn't impossible for a foreigner but not easy either. However, you can try a co-habitation visa but you'd need to apply before you arrive and it takes forever for the bureaucracy to react on simple matters much less important ones such as that. I'm saying this assuming that at least one of you is a Belgian Citizen, if not then you are S O L... The Commune you move into will not be able to process everything within the time constraints if you wait until you are already in Country... They would need to process you first as a foreigner requesting residency which is subject to a boatload of requirements etc.... Then as requesting to change your status once you have already been approved for temporary residency... Not to mention all of the paperwork required which is subject to change from Commune to Commune in regards to marriage... I went through a lawyer and managed to get a "temporary co-habitation visa while I was waiting for the co-habitation visa to be approved. I was in a committed relationship with a Belgian National also. I was required to provide character witnesses(10 minimum) on both sides of the family from both Citizens and friends back home that stated we where in a committed relationship etc etc etc... You can check the government portal on foreigners and request and see if there is a way...It is primarily in french or dutch, very limited english... you need a rudimentary understanding of one of the 3 principle recognized languages and a means of supporting yourself if you are missing anything then you are probably wasting your time...