I don't think it is a legal right ~ try putting your question into the Law section, as there may be legal eagle hanging around in there!
All I know is that if you have a joint mortgage both parties are legally obliged to pay the mortgage. If one doesn't pay then the other has to...both parties are 'jointly and severably liable' to pay.
My neighbour had to sell her house once her youngest child had left school, and the mortgage was paid jointly.
When I split from my ex he didn't pay the mortgage, so when the financial stuff was sorted out after the divorce I had to pay the arrears out of the funds I received. What has to be considered is his need for a home himself, which is why quite a few couples still live together even though they are divorcing..