It does not constitute unfair discrimination on the ground of marital status to limit the right to claim maintenance from a deceased estate to surviving spouses, and not to extend this right to survivors of permanent life partnerships. The discrimination, while based on marital status, is not unfair because: (1) Marriage is a constitutionally recognized institution with invariable legal consequences that arise by operation of law, including a reciprocal duty of support; (2) The Maintenance of Surviving Spouses Act transfers an existing legal duty of support from the deceased spouse to the deceased estate - it does not create a new posthumous duty where none existed during the deceased's lifetime; (3) It is not unfair to distinguish between relationships where a legal duty of support arose by operation of law during the deceased's lifetime (marriage) and relationships where no such duty arose (cohabitation); (4) There are fundamental differences between marriage (where rights and obligations are largely fixed by law) and cohabitation (where the parties are free to continue or withdraw at will without legal obligation); (5) To impose a posthumous duty to maintain where none existed during the deceased's lifetime would be incongruous, unfair, irrational and untenable; (6) The exclusion does not impair the fundamental dignity of cohabitants in a manner that renders the discrimination unfair.