For more than 20 yrs I made dua for marriage and now I have lost hope and feel cursed.
If He delays what you want it means He is giving you something else that He prefers for you and He will give you what you want later and in a way that befits His Power and Generosity. Do not despair but continue du`a which keeps you close to Him! Give shukr for His gifts and He will increase you. Read Rabbana atina fiddunya hasanatan wafil akhirati hasanatan waqina `adhaba ‘n-nar to that intention.
Hajj Gibril Haddad