Section 2D(1) of the Property (Relationships) Act 1976 defines a “de facto relationship” as “a relationship between 2 persons … who live together as a couple”. Although the Act does not define “living together as a couple”, section 2D(2) & (3) provides that “[i]n determining whether 2 persons live together as a couple, all the circumstances of the relationship are to be taken into account, including … [a list of 9 matters]” and that none of these 9 matters is “to be regarded necessary” and “a court is entitled to have regard to such matters, and to attach such weight to any matter, as may seem appropriate … in the circumstances of the case” (emphases added). The seemingly unfettered discretion of the Court, delegated by section 2D, may be helpful in pursuing a fair and just outcome for each case, but it also raises a great concern as to uncertainty. This paper examines some relevant cases and argues that “mutual commitment to a shared life” should be at the core of section 2D and be the most important test, and by which certainty can be found to a large extent, in determining whether a de facto relationship exists. Accordingly, this paper recommends that amendments should be made to the legislation to aid the interpretation and application of section 2D.