Agreed. Each jurisdiction has its own family laws and its own tenancy laws.
If it happened where I live, in Ontario, the Residential Tenancies Act does not apply to people who share a place, regardless of whether they are spouses or not, and “just dating” does not come close to being enough to make a claim in equity, so the roomie would be SOL. In point of fact, it happens here all the time. No notice is required – jist git.