Marriage guidance counsellor

I would probably try the helpline at CHS as a first port of call. They have a lot of information on multi lingual folks like this. https://www.chsbelgium.org/en/ Tel : (02) 648 40 14

If that doesn't bring results, you could try contacting something like the Association pour la Médiation Familiale http://www.amf.be/ and asking if they could recommend someone.

There is also a government register of "authorised" mediators.

https://request.just.fgov.be/cgi-request/mediation/liste-mediateur.pl?lg=fr

Select under
Domaine d'intervention : Mediation Familliale
Langue : Anglais

@P - ok, so I probably answered a bit fast - yes these mediateurs are more along the lines of legal mediators who will help you come to a "deal".

If you're looking more for a marriage counsellor, then I would go straight to CHS and ask them for a referral.

Or you could also try here:
http://www.upccf.be/

Just as a piece of advice, be careful going into any relationship counseling that you accept the possibility that the end result may not be what you want.