The Residential Tenancies Act does not apply to a residential rental agreement that requires (from the beginning of the tenancy) the owner of the property or the owner’s immediate family, which includes spouse, parent, or child/children, to share a kitchen or a bathroom with the renter.

If the renter in your home has to regularly share kitchen or bathroom with the owner in this way, then the normal rules about giving notice do not apply. The rules are instead set by the terms of the tenancy agreement or lease. It is not exactly true that the renter can just walk away from their lease obligations because of a shared living arrangement. They may for example still be taken to Small Claims Court for breach of contract for not paying rent or leaving abruptly and where the landlord experiences a delay in finding a new renter.

In your case you should look at the lease to see if there are any options given for you there. If the lease you are using does not reflect the shared living arrangement, and refers to the Residential Tenancies Act, then this is probably causing part of the confusion, since that law only applies where the renter has their own kitchen and bathroom, or only has to share with other renters.

You may have to look at serving notice to end the agreement because of non-payment by the renter/tenant based on either the lease terms if they share kitchen or bathroom with you, or based on the rules of the Residential Tenancies Act if they do not share.