Is it permissible to have intercourse with one's sick wife using a condom for fear of transmitting a disease, while having another wife?

The nature of the wife's illness and whether it is contagious should be clarified. If it is contagious, then it is permissible to use a condom to prevent harm, based on the Prophet's (peace be upon him) saying: "There should be no harm nor reciprocating harm." However, if there is no harm, then it is not permissible to use a condom except with her permission; this is because the Prophet (peace be upon him) forbade coitus interruptus with a free woman unless she gave her permission, and because a condom might diminish her pleasure from intercourse. The nature of the harm is determined by consulting trustworthy doctors.