In what circumstances will a court allow an unmarried couple to claim the property?

In the comment found in the head note of Pettkus v. Becker - page 168 R.F.L. - the following observation is made by the case commentator; "In Pettkus the Supreme Court of Canada has attempted to come to grips with the problem in an economic and social setting. The relationship more closely resembles married persons than strangers. The same evidentiary problems husbands and wives generate because of their intimate relationship are generated by unmarried couples living together. Not all couples living together should fall within the scope of the decision but only those whose long-standing relationship has generated the trust and lack of formality which surrounds married couples. The search for this boundary may prove to be the most difficult legacy of the decision. The relaxation in matrimonial cases of the principles utilized in 'stranger' property cases justifies the relaxation of such principles in cases of unmarried couples falling within the boundary. What lies unexpressed in the reasons for judgment of Dickson, J., is that current morality will accept the 'special treatment' of unmarried couples."