In Islam, there is no such thing as rape between the husband and wife. However, both spouses should be considerate to one another in their conjugal relationship. If the wife or the husband does not wish to have a relationship due to circumstances, for example, being tired, ill, etc. then that should be considered.
Marriage is not all about conjugal relationship but about love, and compassion for one another.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai