Rights of residence derived from a durable relationship with an EU citizen, are left to a relatively wide discretion of the Member States. Pursuant to Article 2.2 (b) Directive 2004/38/EC (“Directive”), “the partner with whom the Union citizen has contracted a registered partnership, on the basis of the legislation of a Member State, if the legislation of the host Member State treats registered partnerships as equivalent to marriage and in accordance with the conditions laid down in the relevant legislation of the host Member State” qualifies as family member. Provided that they have a durable relationship (duly attested) with an EU citizen, pursuant to Article 3.2(b), unregistered partners are as well beneficiaries of the Directive. The durable relationship was expressly excluded from the scope of Article 2(2)(b): “Unlike the amended proposal, it does not cover de facto durable relationships” (EU Commission, Document 52003SC1293). Article 3 (2)(a) covers “other family members” (no restrictions as to the degree of relatedness) if material support is provided by the EU citizen or by his partner or where serious health grounds strictly require the personal care of the family member by the Union citizen. Pursuant to Article 3.2, “other family members” and unregistered partners can attest a durable relationship, must be facilitated entry and residence, in accordance to the host Member State’s national legislation. In the light of Preamble 6 Directive, the situation of the persons who are not included in the definition of family members, must be considered “in order to maintain the unity of the family in a broader sense”. The questions discussed in this paper are the following: (i) are Member States genuinely considering the concept of durable relationship in view of maintaining the unity of the family in a broader sense? and (ii) how to overcome legal uncertainty and which criteria, both at EU and at international level, can be taken into account in order to assess whether a durable relationship is genuine and should be granted the rights set forth by the Directive?