Can an unmarried couple share a tent in Belgium?

Me and my boyfriend, aged 20 and 21 respectively, are planning a trip across Europe backpacking and camping. We did not expect to encounter any problems with this until I read on the internet that a law in Belgium used to state that unmarried couples under the age of 21 could not share accommodation. Does anyone know if this is still the case (or if it is even true in the first place)? We're leaving in 20 days and I'm getting a bit concerned that we'll be left with nowhere to stay.