Al Bukhari and Muslim reported that the Prophet salla Allahu alaihi wa sallam said: “If a man calls his wife to his bed and she refuses, and he spends the night angry with her, the angels curse her until morning.”
This means that if he calls her and she refuses to give him his rights without any legitimate reason, she will be cursed and Allah will answer their prayers.
But if she refuses because of her illness or if she is afraid that he might be carrying a disease because he cheats on her, this is a legitimate reason