Is the husband's inclination to have sexual relations with his second wife more than his first considered a sin, despite his just treatment of them both in other matters, and is it considered a shortcoming if he is unable to have sexual relations with the first to the same extent?

Justice between wives is obligatory in terms of financial support, housing, and overnight stays, and similar material matters that the husband can control. As for intercourse, equality is not obligatory therein; rather, it is according to natural inclination. However, it is forbidden to refrain from intercourse with one of them to save desire for another. As for inclination and love of the heart, there is no sin in it.